I know this sounds crazy, believe me, I know. I have been thinking about the Wii U Virtual Console's lack of GCN games and the fact that the Wii U Pro Controller can't really accommodate them. This got me wondering why it seemed as though there were plans way back before the console launched to have GCN games downloadable from the eShop, but no announcements could be made at the time (or now apparently), and that's when it kind of clicked. Nintendo isn't really held up by hardware or legal issues with GCN titles (well, maybe some legal issues for many 3rd party titles) I think they are working on new hardware. A kind of Wii U Classic Controller.
I know what you're thinking! They have the Wii U Pro Controller, it is sufficient. Yes, for the most part, it is. The Pro Controller was designed specifically for use with Wii U and most VC games, but what about games that used pressure sensitive triggers? For that you need something akin the Classic Controller on the Wii. Of course, redesigned for two things; GCN games and N64 games. This would also explain partially why there are no N64 games yet. This Wii U Classic controller would be designed specifically to make playing GCN and N64 games a lot less awkward, since the Classic Controller for the Wii was kind of weird when playing N64 games. I mean... for me, if I'm being 100% honest, I hated the Wii's Classic Controller when playing N64 VC games and I ended up using my GCN controller. Always.
So... I think this is what they're working on. I could be wrong, but it makes a lot of sense...