I feel like the Wii U simply isn't going to be remember as fondly as the GC was... the GC had a fantastic line-up of 1st party games, while two of the best Wii U games have already hit the Switch (BotW and MK8). I'm sure the games will go up in value, that's a no brainier since it's Nintendo.
I had a GC and PS2 back in the day and I spent way more time on the GC than I did the PS2. I have a PS4/Wii U now and I barely touched by Wii U. Prime 1/2, Wind Waker, Sunshine, Melee, FE PoR, Double Dash, Pikmin 1/2, and Eternal Darkness simply outclass BotW (also on Switch), SM3D World, MK8 (better version on Switch), Smash, SM Maker, Bayo 2, Pikmin 3, Xeno X, and WWHD (remake).
Third party support on both systems were bad but I actually bought a quote a few third party games on my GC simply because they were just as good as the PS2 release or better, and third party support on the GC was fairly consistent. On the Wii U, I think I only have 2: Rayman Legends (Wii U is easily the best) and MN9 (it was $6) but that's offset by tons of great indie releases I guess (all of which I bought on the PS4 or PC, because they run better on the PS4/PC and Nintendo's online infrastructure sucks).