those examples you gave were because SF3 and MvC2 were originally released on dreamcast, and SF3, worst of all, released long years after the arcade release. don't think it is representative. compare to SF2 on SNES. it's a huge fall in sales, it wouldn't be rare that the psn version of those games outdid the dreamcast release
a lot of the skullgirls sales has been sales through the years; the game recouped costs fairly quick tho, yeah
gotta remember that skullgirls was a 8 character game initially and only later on a few more were added, so costs for a non anemic DS game would be higher.
I don't think it is a bad idea, hell, it would probably recoup costs easily, but DS by the skullgirls guys would need to have a better sales model than Skullgirls and SF5 had. again, capcom cannot figure out how to get their second biggest franchise to sell well, and you are asking them to partner with western developers for a niche title, that's a huge risk no matter what