While there are many different possible answers to what is this new tank-like vehicle, I'd like to point out that the role of the tank itself may be rapidly changing for the future battlefields. Especially for China, which seems to have some specific mission sets in mind.
The only possible battlefield where a big, heavy tank might be used in numbers would be in the Korean peninsula. Even there, the geography is actually not very well suited to such vehicles. But it's still more permissive than in two other plausible battlefields. Against India, where we saw a very light tank developed for that high rise region.
And against Taiwan. Which would be a very specific battle with specific needs. There, China would profit from a light vehicle, so more can be brought to the island in any given time frame, and one with less supplies needed to maintain it. Again a lighter vehicle wins there.
Furthermore, why have we even seen a 120mm or 125mm gun appear on tanks? Despite the fact that most of tank's targets during the decades were various non-tank vehicles, bunkers, infantry groups and so on - for which lower calibers such as 105mm were quite adequate - we saw the transition to the larger caliber. Solely because of enemy tanks being able to withstand the lower caliber weapons.
If one removes most of enemy tanks as targets - then the 120mm or bigger calibers become mostly superflous.
Even the heavy ifvs of tomorrow will not be able to withstand 105mm rounds. At best, some future monster super heavy APC, without a turret, might be able to take on a 105mm round. But those are unlikely to become the norm on the battlefield due to their demanding logistical footprint and because they'd be magnets for air power.
By air power I mean pretty much all means of guided weapon strikes coming from the air. And that's largely the reason why tanks themselves, as any other heavy vehicle, might not be target sets of the new vehicle.
Basically, such a class of a vehicle might be more of a mop up vehicle. A cheaper way to provide firepower to the infantry, against already battered enemy in the trenches opposing them. Before any sort of large formation comes to Taiwan, be it with heavy tanks of today or with those future lighter tanks, it's possible we'll see a very thorough cleansing of the battlefield from the air. So much so that opposing combat vehicles will simply not exist in high numbers.
