I'd say the 512 colours on screen (potentially all on the same scanline) poses a greater issue than the Sprite HW. Sure, the A1200 can't display as many sprites, but it can at least display the same number of Sprite pixels per line.
Anyway, my answer is also no. I don't see it happen.
On the other hand, the PC-Engine can't emulate an A500 either because it can do things the PC-E can't, so swings and roundabouts
