We need to see the following with PLA:
- Overwhelming dominance and control of air space of Taiwan. That requires ability to sustain large aircraft formations for long period of time. (this is the most important)
- Large fleet of Y-20s able to drop a lot of troops and tanks into Taiwan.
- More LHDs and LPDs able to transport a lot of amphibious combat vehicles, troops into Taiwan
- A lot more helicopters - both of attack and transport variety. Need to see Type 075s with a large horde of attack helicopter.
- UCAVs that can take out Taiwanese armored vehicle when given complete air control
All of the above can be achieved in the next few years.
I think the threat of SAMs, all the way down to even MANPADs, means that I can't see Y-20s playing a significant role until much later in any Taiwan contingency after the island has been relatively sanitized of military opposition.
Given the trajectory of cross strait military balance, I think the ability of the PLA to defeat ROCAF and ROCN symmetric forces (fighters, navy surface combatants, large fixed sites such as air bases C4I centers and large depots etc) and significantly suppress ROC SAM capabilities, is not really much of a question anymore.
But a vulnerable phase will remain based on the current systems the PLA have procured (or rather not procured), specifically at the actual "amphibious assault/invasion" phase of the operation.
Crossposting and paraphrasing from CDF, something I wrote a little while ago:
I think there are 5 systems that the PLA needs to prioritize to either induct in service, or induct service in larger numbers, to build on their current likely Taiwan oriented orbat/TOE, which would ensure a higher chance of success.
Specifically, I think at this stage the greatest point of weakness for the PLA is the initial amphibious assault phase of the invasion and the establishment of the beach head, where ROC forces are orienting many of the procurement to organize a counter attack. Needless to say, if initial landed forces can be hampered or even if amphibious assault ships can be struck during the assault phase, that could cripple the actual ability to carry out an invasion, even if the PLA had already defeated the ROCN and ROCAF prior.
This phase of the scenario is likely the greatest "vulnerable phase" that remains, where the ROC military has the best chance of crippling the invasion and where the current structure of PLA forces is not ideally suited to guarantee.
In order of priority, I think the top 5 systems that are all well within industry capability (and only dependent on military commitment and procurement), with the greatest potential to mitigate if not reverse the "vulnerable phase" will be:
1. Stand-off range synthetic aperture radar pods
2. Direct attack PGMs of 250kg and 100kg weight classes with MERs
3. More amphibious assault ships
4. Better MR SAM capability
5. Multirole naval helicopters
These are all systems that are either in service, or very much accessible to the PLA if they deemed them a requirement.
1. stand-off range synthetic aperture radar pods.
You need to be able to see what you want to destroy, and you need to be able to see in all weather, aboard multiple different platforms if possible (in a redundant way so that they are dynamic and difficult to attrit). At present the PLA's major airborne SAR platforms is the Tu-154Ms, which are okay, but somewhat limited in number, relatively vulnerable, and ageing. A podded system like the US AN/ASQ-236 Dragon Eye can be fitted onto fighter aircraft, and while they are much smaller than something like the PLA's Tu-154M and the US 707 based E-8 JSTARS, what the podded system does offer is that you can have multiple fighter aircraft in the air with SARs, that are far more survivable and able to defend itself if needed, and able to move to quickly cover areas of interest as they pop up.
Obviously such a system would be networked with airborne and ground based command platforms and nodes.
Multiple SAR pods in the air will be particularly important during the initial amphibious assault phase of the invasion, whereby the ROC Army would likely try to organize their remaining forces for a counter attack, and it would be important that the PLA have the high quality GMTI of all of the surrounding 50+ kilometers (if not more) outside of the initial beach to rapidly detect, identify and interdict reinforcement columns, in all weather conditions.
2. Direct Attack PGMs in the 250kg and 100kg categories, with multi-ejector racks.
This sort of goes without saying. Currently the PLA's smallest air launched DA PGM in mainline service is the 500kg LGB (maybe newer variants have satellite guidance augmentation). They need weapons that are smaller to allow a single sortie to engage more targets, to increase magazine size. These PGMs would be important not only for striking air bases, depots, and other facilities after SEAD/DEAD, but also is vital to allow for dynamic interdiction of ROCA ground forces to support initial landed amphibious/marines units.
Flankers, JH-7/As, J-10s, H-6Ks with multi ejector racks with 250kg or 100kg bombs, with satellite and/or laser guidance, and wing extension kits, are of course nothing new to the Chinese aero industry, it's just a matter of the PLA feeling comfortable enough with achieving air superiority to put a bit of money into a modern and robust DA PGM arsenal.
3. More amphibious assault ships.
This one is also pretty simple -- more amphibious assault ships, means the larger the first assault wave. The larger the first assault wave, the greater the chance of establishing a successful beachhead.
More 071s, more 075s, more LSTs.
4. Better MR SAM capability -- either quad pack MR SAM (3-5), and/or enhanced 054As with enhanced HQ-16 variants, and/or 054B, to escort said amphibious assault ships.
The ROC military would likely exploit this vulnerable phase where the PLAN's amphibious assault ships are less than a dozen km off the coast, to blindly launch as many AShMs in the general direction as possible. Some people have argued that ROC AShMs are useless without OTH guidance (which the PLA would have largely destroyed) -- and that is only partially true.
The nature of AShMs is that they all have terminal guidance, meaning they can be launched "blind" so long as you know that enemy ships are in a general direction, and program the terminal guidance to activate in a general area.
If a sufficient mass of AShMs can be launched at once in that way, they could still prove to be deadly threats.
While I'm sure PLA aerial AEW&C and fighter CAP would be able to provide significant warning and reduce their numbers, the last line of defense would be the frigates and medium destroyers escorting the amphibious assault ships providing area air defense -- and it is MR SAMs that would do the brunt of that work.
(Needless to say, multi-domain networking between airborne assets and surface and naval air defenses would be somewhat expected and assist to increase the effectiveness of the SAMs, but possessing a large magazine of multi-simultaneous targeting capable SAMs is still needed, and I think modern quad packable MR SAMs are probably the best option for this.)
5. Multirole naval helicopters (ASW, minehunting, anti surface) -- basically Z-20F
Again, goes without saying. The importance to do ASW, to hunt mines, and conduct anti surface/ship missions against FACs is very important during an invasion in the "vulnerable phase".
Other worthy mentions, if I was to extend this to top 10, would also include more 370mm MLRS, MALE UAVs/UCAVs (WL-2 pattern), J-16D, J-20, transport helicopters.