An FPGA based Amiga Video Toaster does not have to only be NTSC, it could support many resolutions including PAL & even HD.
Has anyone ever expressed any interest to work on this stuff? I took a look at some part of it once and it was something like ~100k lines of assembler, and this was just one component.
So the emphasis is very much on "could".
Frankly, I don't see the point. It'd be much easier to emulate the thing in SW anyway, if you must. Just take UAE and add the required things. FPGA is possible, too, but what benefits does it offer over pure sw solution?