Yes it will flop and I'll tell you why. The advertising is abysmal, first of all.
Have you seen the trailers?
http://www.youtube.com/watch?v=Yq-Yqt52w48
That's just a general "hype" trailer. The character trailers are the worst.
http://www.youtube.com/watch?v=hvAtu33qTh4
To compare...
http://www.youtube.com/watch?v=F4yBT3XLUxc
http://www.youtube.com/watch?v=8PgxEQuFp2c
It has almost no personality in comparision, it's pretty bad. The music in the background of the PSAS trailers is really dumb, and no hype is generated. No themes for the characters.
If they made good cinematic trailers like Smash Bros, or good theming videos like UMvC, more people would be excited. But no.
It doesn't look like a bad game, while I'm not a huge fan of super only can kill (imbalanced gameplay to be expected), it might be a fun game all around. I haven't tried it yet; I will soon.
