Since by late bloomer you think 50+ mil - no way. It will keep on selling better and better, but will struggle to outsell GCN.
You can't compare Wii U to PS3. Such comparisons is just grasping at straws. PS3 was a state-of-the-art console, the most powerful one on the market and very, very expensive. Many people were like "I want one, but I can't afford it now, so I'll wait 2-3 years". And so they did, that's why the console bloomed later on, cause after these 2-3 years it still was the most powerful and advance console on the market. No such thing is correct for Wii U. It has been outdated the day they announced it, it's the cheapest console of its generation (though only slightly), so everyone who may want it, can get it.
And the final nail in the coffin is the departure of 3rd parties. 50 mil is absurd. A steady improvement? It's a given, but GCN numbers will be a success at this point.
Wii U is a GCN 2 - I called it months before the release!
My Vita to-buy list: The Walking Dead, Persona 4 Golden, Need for Speed: Most Wanted, TearAway, Ys: Memories of Celceta, Muramasa: The Demon Blade, History: Legends of War, FIFA 13, Final Fantasy HD X, X-2, Worms Revolution Extreme, The Amazing Spiderman, Batman: Arkham Origins Blackgate - too many no-gaemz :/
My consoles: PS2 Slim, PS3 Slim 320 GB, PSV 32 GB, Wii, DSi.