It had 1 year with zero competition, then 1 year with competitors with few blockbusters. Next year PS4 and X1 will be all guns blazing and we will probably see X1 keeping the same price from Q4 2014 and maybe PS4 matching it (at least in the end of 2015).

I think competition will be harsher next year, so I wouldn't count on 6-8M. However, I think it can pass the GC, but not by beating its peak. It can outleg it. It depends if Sony and MS will go with a regular 5 years gen or an extended 7 years one. Either way, Nintendo will have to follow the trend and support the Wii U during this time. They won't release a new console with more than 1 year of advantage against PS5/X2. That would be Dreamcasting themselves.

Factor in there will announced more games as the year goes on and also factor if they drop the price to around $250, sales will go up again. So yeah 2015 could easily be Wii U's peak year

That trail of thought makes no sense to me.

How does the frequency in which these games release affect their system selling ability? If someone wants to buy a Wii U for any of the games that come out next year then they'll buy the system for that game when the game releases. Why would anyone not buy a Wii U for, let's say, Kirby when he wants one for Kirby, just because the game releases with no immediate other game releasing close to it.

If all the announced 2015 games from Nintendo release in 2015 then all the people that want to buy a Wii U for any of those games should be buying one no matter if all the games release in Oct-Dec or if they put one out every month.

They have already released there two biggest series Mario Kart and Smash. This is the peak year.

Also, don't forget that two years into the Gamecube's life it had two price cuts and was already being sold at $99. The Wii U really hasn't seen a formal price-cut yet (as long as you exclude Nintendo dropping the 32GB model down to $300). I think next year we will for sure at least see a Wii U price cut, maybe with even a $200 "slim" version getting introduced. This could have quite an impact on sales.

Also don't forget that games like Mario Maker, Splatoon and Star Fox will be getting released next year. On the surface these games don't look like big console movers but I think the potential for at least one of these titles to catch fire is pretty high. I mean, what if Splatoon turns out to be the "next" Portal?

I totally forgot about possible game announcements and the inevitable price cut. Those should help some as well.

Wii U is not going to reach 5m this year, and yes it will do better next year because there's almost a game every month. Even though there aren't titans like Mario Kart 8 and Smash next year, Zelda should provide a decent boost and other games should at least keep the console higher than 30k weekly

On what basis?

Nah there's enough software to keep it going next year, but a price cut in 2016 would keep it with legs

The competition is going to be much more stout in 2015, only way the wii u peaks next year is if they implement a price cut and it would probably take a significant one at that.