So if the A1000 (the real one) had been bog-standard IBM-AT-clone with an 68000 in the place where one would expect the 80286 and some obscure IO-chip clued to it, it would have triggered the same reactions like the A1000 with it's outstanding GFX, sound an OS had ?
It say the actual reaction would be lukewarm at best.
At the time the AT was current, I'd say yes it might have.
The 68K would have been able to run decent multitasking OS' (Xenix, OS9, Minix). The 80286 would have been far less capable.
The system you describe would have made a great server, multiple terminals could have been run from it.
Overall it would have been clearly superior to the Intel based alternative.
Further, as the Amiga advanced, that outstanding Graphics and Sound system you mention was a bottleneck to faster processors. By the end of the Amiga's life cycle RTG and other replacements for the original chipset made sense. And finally the move to PPC (since the 68060 topped out at less than 100Mhz) also made sense.
Only the OS was really worth retaining and now its a little long in the tooth.