I used to think that reaching N64 numbers would be achievable for Wii U... used to!
You can't really compare GC with Wii U.
Nowdays, even being on the market for almost 10 years, both the XB360 and PS3 still have a price tag between 150 and 200€ (didn't check the US market) when they could easily get the price down to 99€. But they won't: profits and recouping losses being the reason.
Wii U still has to fully recoup it's R&D and losses suffered until last year.
Going below 200€ just won't be an option for Wii U when the console is still selling so low.
Can the console last the usual 5 years?
I highly doubt that can happen. And if it can't, then it will really be a miracle if they even reach GC's numbers.
They don't have the 3rd party support that the GC had to offset the lack of 1st party games when Nintendo starts developing for next gen; sales are so low that when they start going down, retailers will probably react like they did in 2013 (low support meant small orders and return of inventory).
If E3 this year you don't see the a good number of titles for next year, like you saw last year, in regard to 2015, than you can bet that support for Wii U has entered the phase of decline.
Less support = less reasons to buy Wii U.
