I think it just missed its audience, and it didn't have the appeal of Snake being in SSBB behind it.
But I'm not at the point where I'm throwing down money on this as a guarantee and I won't argue it to death because I don't think anyone enjoys that.
We'll wait and see. I do hope something comes of this, though, like a MGS spinoff, but Kojima has expressed how absolutely sick of MGS he is, hence why I doubt a whole new game.