Blade has the entire vampire mythology to draw weapons and fighting techniques from (or vampire killing in his case), so I don't think he'd be found wanting for interesting moves to utilize. Yes, there'd be some similarities with Dante and Deadpool, but he's still unique enough that he'd be well worth including IMHO.
Also, something that EVERYONE from Capcom to the fans who are supporting everything they've done so far are forgetting in regards to whether or not fan favorites should be in MVC3 rather than "characters that make sense," is that MVC3 is nothing without one simple compound word: fanservice. The whole reason the game is Marvel vs. Capcom and not just some other fighting franchise is because it gives you the chance to make your favorite characters fight each other. When Capcom deliberately snubs fan favorites like Mega Man because they want someone with a more "unique" fighting style, or when Marvel pads up their entire half of the roster with product placement for their latest multimedia ventures, they are in a way betraying the very spirit of what made the MVC franchise enjoyable in the first place.
Imagine if Nintendo left Mario out of the next Smash Bros. game because "his fighting style is boring" and replaced him with Lanky Kong. Yeah, Lanky Kong would offer a more unique fighting style that could potentially balance out the roster selection better, but he has no-where near the popularity of Mario, and the longtime fans of the series would feel like the game isn't complete if they can't have Mario in there tearing stuff up. When you do a crossover game, half of the appeal is based on whether or not your favorite characters are in the game, and if you're expected to learn to love a bunch of obscure characters who all but a few players are unfamiliar with, then you might as well just take a whack at an entirely new fighting game since either way you won't be looking at many familiar faces.
I'm not saying that MVC3 sucks because they didn't included Mega Man or Gambit, but I can't say that the drift away from using fan-favorites hasn't lessened the appeal to a notable degree, and I am hardly the only MVC fan who feels this way-- especially since Marvel and Capcom have already had two times already to include the characters who players have been clamoring for the most.
