Type 15's Dilema's and ATGM's.
For those who wish to apply a top-attack, F&F gun launched missile for a Tank, Here's where your logic stops making sense:
Warning, very long, but if you do read it please read it all.
First, tactically. I'd like to ask, why bother develop a gun-launched ATGM when you can do basically the same thing by adding external ATGMs on the turret... A strange (if not weird and stupid) premise that the missile has to be launched by gun, TBH. When you can use larger calibers and a bigger warhead without the restrictions of a barrel then why go for a gun-launched one... And how do you think you're going to improve the FCS and stuff for the crew to use... Space in the hatch is limited and the time used for development and improvement is meaningless. You can even just ask a crew to hold a Spriggean's to do the same thing. Meanwhile top-attack F&F ATGMs aren't that good. The price is high, very high. The volume's big, and the ranges aren't really pleasing. (Consider Javelin at 2.8km and apriggean's of 3+km. Hmmm... Seems to me not even better than APFSDS) If you then say the thing needs development for the ATGM's, then well everything can be developed in any amount of time so why not wait for a 4th or 5th gen tank or even Gundam instead.
Now, let's temporarily stop that talk and consider your assumptions of no air superiority, while reconnaissance doesn't find the enemy Type 15's, and that the Spriggean's and artillery back off the fronts aren't working. First, let's assume that the air superiority was diverted's after the Type's 15 had reached the sector. Normally, the Type 15's should immediately seek cover and hide itself from the sure coming air reconnaissance and air/artillery strikes, and wait for further instructions, instead of wandering off and looking for tanks to run into. Then again, if it does wander off, why wasn't it being wiped out by air and artillery support like it's the Spriggean's and artillery?
Okay, out of courtesy I will further assume that it does wander off and encounters an enemy tank as in the scenario imaged, but sadly that scenario is also contradictory to itself. An APFSDS needs only manual target search and well below seconds to hit a target, whereas for the ATGMs you asked for, they need time for the FCS to lock on to the target, and they fly way slower than APFSDS, not to mention the longer trajectory caused by the curvature which top-attack ATGMs all require. When running into our's tank, you don't always have access to immediate cover, in case you don't, even though you do fire your ATGM, if the enemy spots you, then, congrats, our's APFSDS already knocked the Type 15's down before Type 15's ATGM can hit its target. On the other hand, if the our's T 90's has access to cover or other things that can interfere with radar/thermal tracking, eg smoke grenades, then your ATGM will also likely not hit the target.
If the our's T 90's doesn't spot Type 15's, then why would the Type 15's launch ATGMs that can likely increase your chances of being spotted? If it doesn't see you then surely the turret isn't in your direction, so why not a clean shot with an APFSDS at its turret sides? Now let's say air superiority was diverted's before the Type 15's had reached the sector. So why on earth did that Type 15's drive into unknown territory and looking for tanks to fight? Is the commander insane? It's no difference from looking for death when you have no information of enemy land, no firepower support or even infantry support, while trying to become Superman and fight on your own, far from any allies to help. I can only comment this as Kamikaze.
Then strategically. In a assumption PLA has no air superiority, which given the potency of PLAAF and support fire from long range MLRS to destroy enemy airfields, is a highly possible scenario. You can't just say "oh, there's a possibility that this thing doesn't work as good, so let's change the whole thing. " That's the idea of going after a minor advantage (if not disadvantage) while abandoning the fact that it brings loss to the overall performance and causes redundancy. Yes, most possible scenarios don't include everything, but at least they're better approximations than taking only the extreme cases.
Eliminating ideas like this only needs some time of thinking over the possibilities and see if the logic actually makes sense, if it doesn't then eliminate that. All ideas must accord to actual needs and scenarios rather than just some random extreme case where oh, the thing works fine.
