I guess that topping must have strategy for future. With this preamp they fulfilled line of small, desktop-like devices and it`s also quite new to audio world. Small but well regarded, with amazing reviews they building company reputation. For this particular unit, small size is it`s limitation, and it is small to fit company lineup. As someone said: bigger unit means a lot of problems like stupid things like storage space. Albo bigger unit means more weight, more weight more materials and so on..
I believe that Topping is capable of making preamp with 2021yr functionality, a lot of inputs etc. but it`s not the time for them for such investment. I have no idea what Topping plans for the future but power amp would be natural to be next, and that would change everything as even smallest mono Class-d amp with decent power output would need bigger chassis that any current device from they offer. So to match new lineup new preamp would be needed. It means more expensive gear, and another issue: who would pay for it? To offer that kind of equipment Topping needs to go deeper into hifi market to find costumers. Maybe they should present their gear during Audioshows around the world. That would be awesome.