On a technical level it's possible.
The FPGAArcade, which is almost shipping to first batch, is pretty close. It's not too large and does AGA (68000 currently, but I hear there are other cores in the works). There are demos of it running some AGA games..
And it's expansion connecter sounds like it could be made to work with an Amiga keyboard port and floppy (with some FPGA work I believe)..
I don't see PCMCIA happening tho...
And it's not too large..
But, it's market is Amiga, ST, and Arcade enthusiasts...
Redesigning it to fit nicely in a 1200 case is "possible", but is it worth it for anyone to actually do that??