I am not so sure Hyrule Warriors won't be a system seller. I know the mainline Zelda games sell great and die hard Zelda fans love the same old same old, but I know a lot of people, myself included, who love Zelda games but have gotten tired of the same old formula and are liking the idea of a new type of Zelda game. Obviously it would need a major ad campaign to be that game but the consensus among Zelda fans is it will suck but I am not so sure.
On the topic of revealing a game early I don't think that is a new thing or a good thing in itself, they have shown games in the past that got people hyped up that never materialized, remember Project HAMMER, or Super Mario 128? As for E3, I am still not convinced their new strategy is the best but I don't think it will kill them I think if anything it is just a sign they are pinching their pennies instead of throwing money around like MS or Sony would do. I think that is smart for a small company losing money and feeling the pressure to diversify their portfolio.
I am also super excited for any new console that/hand held that can unify their entire game division under one platform, I have been wanting that for a long time. It always bothers me how their handhelds get the games and the attention their consoles deserve so if this will bring everything together I am in. I am not sure about the rest of the world but between the Hyrule Warriors, the new figurines, and Mega Man in Smash Bros and if true Pac-Man being in the game too would help build up some hype.
Actually for me personally I have been on the fence for a while but after watching some ACGN videos recently on the Wii U covering NES Remix and a couple other videos I am starting to think I might be getting one sooner than I planned now that I have a second job.