I mean, I think you provided your answer for the dilemma you posed.
Alternatively, the monkey paw curls solution to your question is that they can certainly cease all hypergolic launches and go cryogenic only, but of course with the resulting consequence that their annual launch capacity is gong to nosedive.
There's no reason why they can't ramp up their production and rate launch rate to be similar to the old hypergolic rockets. Just look at all this new private companies with much less funding and staff that are preparing to ramp up their lift rate to more then a dozen times a year, having factories that can produce hundreds of new engines and also doing working on brand new reusable rockets. Landspace's plan is to double their launches every year for the next 3 years. Cryogenic rockets give much better performance anyway. The better logistics you can get from consolidating everything to a standard technology and not having to deal with two wildly different engines and fuel types, one of which is very toxic and requires much more stringent safely measures should make up for it in the long run anyway.
It's not like I'm asking them to entirely move to cryogenic the year that the long march 7 came out in 2016, but it's almost 2024 and the long march 2/3/4 is still taking up more than half of China's launches. That's billions of yuan, thousands of people and massive factories all dedicated to a 50 year technology that's basically at a dead end.
There is no reason why that would happen. The Long March 7 was precisely designed to use the same tooling and production facilities as in the Long March 2 and 3. It uses same diameter modules and everything so transportation would also be the same. There is simply no good reason that I can see why they haven't replaced both Long March 2 and 3 with Long March 7 derivatives.
What if the launch cost of CZ-2 and 3 are dirt cheap? Wasn't there a figure posted in this thread saying that CZ-2 launch cost was slightly higher than Falcon-9 in reusable mode? That would mean that old CZs are much cheaper than the new CZs.
Remember CZ-7 was designed to be crew rated, so it by design has a lot of extra masses. It is by nature nothing to compete with old CZs in cost without large amount of change which doesn't really worth it.
There's also the long march 6 and 8.
What if the launch cost of CZ-2 and 3 are dirt cheap? Wasn't there a figure posted in this thread saying that CZ-2 launch cost was slightly higher than Falcon-9 in reusable mode? That would mean that old CZs are much cheaper than the new CZs.
There's other factors at play here. For one, consolidating all your logistics to support cryogenics will make all the other rockets cheaper. After all, that's two groups of factories, two different sets of tooling and engines, two groups of engineers working on two wildly different engine types that cannot benefit much from development on each other. For launch sites, that's two groups of different fuel that they have to store and support, one of which is very toxic. For training and talent it's not good too. That's lots of talented people working on a dead end technology, if someone was working on the long march 7 and figured out a way to chill the propellant more efficiently, that's knowledge that can be applied to every cryogenic rocket going forward, even to the Long march 9. If someone made an alloy that won't melt under liquid oxygen at 300 bar, that benefits all future cryogenic rockets, because they're all working with liquid oxygen. Meanwhile any improvements to N2O4 / UDMH fuels or engines will be solely limited to the long march 2/3/4 and ICBMs.
Just look at the private space sector, they get most of their staff from the government space sector. Imagine a very talented engineer wants to jump ship to a private company, issue is that he has worked on hypergolic fuels and engines for most of his career and his skillset isn't the most useful, thus his talents are wasted on an obsolete technology.
Cryogenic rocket give much better performance anyway. Sure the long march 3 is cheap, but it's useless if you want to launch a single payload of >5 tons into LEO.
You could use for the "Cheaper" argument for literally anything. Why use guns, just pick up rocks from the ground and throw them at the enemy. Infinite ammo. Why develop cars when legs are free? Why develop farming when you can pick up free fruits and vegetables in the forest? I don't think a single new techologny in history started off cheaper or better, the prototypes always costed more and were worse and only became cheaper and better once more developed.
the problem is that none of them have a platform as ambitious as CZ-10 family or CZ-9 in the immediate pipeline.
Landspace is planning for a fully reusable Starship like rocket by 2030