The answer is "Maybe..." From what I recall, Steve at Botbitz has concentrated on just one family of MCU as he needed to buy a fairly expensive dev kit and some software. You could modify an ESC with just about any MCU but if you change to an ESC with a different brand of MCU, you are up for extra expense.

Other factors:

The code needs to be unlocked or unencrypted. Some MCUs have an option to lock the code permanently, so even if you can read it, it can never be changed. Luckily, it seems that most Chinese ESCs are unlocked.

The MCU and/or the programming pins need to be accessible. If the MCU is buried between two PCBs, its often impossible to re-program it and you have to buy the ESC to find out.

You need to be a super-genius like Steve

BTW: I added a larger heatsink to a TZ85 and used it to run a Magmotor @ 22 volts last year - the ESC hardly got warm in testing. Steve is looking at running long Mag motors in his heavyweight using one or two TZ85's.