Betamax was brilliant, but is there anyone who would bring a tape based video recorder back into there house?
Yes, Amiga was brilliant, but the OS needs a complete rewrite to be competitive, then none of the retro software would work and the remaining Amiga people would be ticked off.
What you would need to do is throw out what we call Amiga Dos and start again building the Workbench GUI on top of a UN*X variant. QNX was a good idea, unfortunately KMOS/Amiga Inc pissed on it and the deal is long dead.
And then you still need a reason for people to switch, there's no modern software out there for Amiga and there's no brilliant idea that would make it a hit. You could spend tens of millions on development and 22 people would buy it.