MwRYum
Major
Z-9 was the best that China can get in terms of helicopter platform of such weight class and size, but everyone knows how lacking it is for a good blend of endurance and loadout potential, but the Z-8 series is too large. Thus back in the day when the Z-20 is nothing more than a rough model displayed in airshow, but the Z-15 is officially announced as a Sino-France joint project, people begin to pin their hope onto the Z-15, even when the nature of Z-15 project would make a military variant difficult to materialise.I don't think Z-15 was ever mentioned as a military project, let alone a PLAN platform. While, of course, it may happen sometime in the future, so far there don't seem to be any plans for such a helicopter. All we had was Z-15 being "a helicopter" of nice enough class that many people just jumped to conlusion with that it's definitely going to be military helo. Maybe, some day. But not soon.
As for Z-20, we definitely know it's being developed as a military helo, but for now all we've seen is a PLA utility variant. A PLAN variant would need certain changes. Again, it may be in the pipeline but it may be several years in the future, if it happens.
Even if Z-20 or Z-15 (i really doubt both would be used within PLAN, as they're too close in capability) get their naval variant and production starts - it would take at least another decade of production until produced volume gets to satisfactory level and most Z9 are replaced.
With all the above, I'd say PLAN very, very much counts on Z9 being its most numerous ASW helicopter for at least next 10-15 years, and plans to use Z9 (even if by then other models get used in greater numbers) for the next 20-25 years.
Which brings me to the new mystery missile - alleged winged torpedo carrying missile. Layout and size points to a long range, fairly long loiter torpedo carrying platform. That itself is a very strange concept - as usually a helicopter carrying torpedos is more efficient. BUT, usually, ASW helicopter isn't a tiny Z9. Z9 is very, very much limited by its size. It can carry the full sensor package and full fuel. Or it can carry almost full fuel and one torpedo. Or it can save further on fuel and carry two torpedoes. It's loiter time over target area is quite small and probably unsatisfactory for modern ASW combat. Which is maybe why we're seeing the new mystery missile- to completement Z9 and alleviate their limitations. Z9 could then carry no torpedoes and stay in air for a fairly long time, using their sensors, and other platforms can fire the torpedoes when needed, even have them stay in air and loiter near the target (For quick reaction) if situation requires it.
Now, though, with the Z-20 moving ahead, a pure-bred military helicopter platform has moved into flight testing stages, hopes for a more capable, navalised helicopter for the PLAN, one that can operate from almost all flight deck in the PLAN fleet (tight for 056 perhaps?),becomes very hopeful for the first time.
Of course, not necessary would it mean that the Z-20 will replace all Z-9 airframe immediately, probably we can expect some Z-9s that still has good amount of airframe lifespan would be re-assigned to other roles. But I don't expect that to happen before 2020, somewhere near mid-2020s is my estimation.