Patents can not be renewed- trademarks/servicemarks yes, copyrights- seemingly effectively if various lobbies have their way but not patents.
Back on topic as others said there are several quite viable alternatives and dumping GBA saves is not that hard to sort out either (a cheap and cheerful second hand DS).
That said I suppose we could ponder what it might take. No chance of anybody really wanting to write a Gameboy line emulator for the N64 by my reckoning so hardware it is. N64 is mips so the ARM of the GBA and Z80 a like of the GBC will need to be taken care of, actual hardware works for me but I can certainly not ignore the system on a chip stuff.
http://www.crazynation.org/N64/n64_cart_info.htm for want of a better site will be my reference for the cart edge.
Sadly there is no video passthrough and no controller passthrough so my idea of a "just powered by the N64" a la the old GBA radio addons is probably not worth pursuing. That said making a controller adapter will probably not be that bad.
The question probably then becomes how do you play it with regards to piping the video down into the N64 and out or ignoring that and going out through the back of the would be wideboy64 emulator. I am not sure about bandwidth though it will probably not be that bad even if you did go fully uncompressed stream (240x160 for the GBA and 160x144 for the GB/GBC, if you figured out a way to punt things to the N64's visual memory it might be even easier.
I can not really see it being viable for anything when you could probably just emulate it or get a standalone device (the K101 features an AV-Out jack) not to mention dodge a bullet with the N64's less than stellar video output (
http://gbatemp.net/threads/need-help-tracking-down-a-resistor.324709/ ).
Now if you want to break a K101 or something and stick an external controller of some form onto it then we can definitely talk about that. It probably will not even be that hard as long as you can solder and have some funds to play with.