More like how i'd have done commodore:
Stop developing 8-bit computers after the c64, but give it a ram slot and sell models with higher ram. Make a constant effort to miniturize the design.
Released the 500 and 2000 in 1985.
Make a C64 compatability card for amiga.
Clone the 68K archetecture. MOS tech is right there, so use it guys. motorola aren't doing anything special.
Put a ton of funding into developing a new chipset for release in 1990. chipset should be capble of chunky, and have atleast a simple 3D accelerator that could do texture mapping. Think "almost playstation", like ocs was "almost megadrive". Monitor drivers that include 800x600 and 1024x768 are needed too.
Develop the hell out of the OS.
skip 500+, 600, cdtv, and those stupid commodore PCs. Release the 1200 and 4000 in 1990 CPU should be socketed and a range of speeds avalible. use HD floppys in the 1200.
behold, a non bankrupt commodore.