No, it doesn't. Major financial institutions invest significantly in technology and many are already actively exploring the blockchain[1].
I wouldn't go so far as to say that the Winklevii can't stake out a position in the broader blockchain market, but a Bitcoin exchange isn't likely to help them establish a meaningful position.
[1] http://www.bloomberg.com/news/features/2015-09-01/blythe-mas...
> Major financial institutions invest significantly in technology...
That they may be, but that's no guarantee of success or domination. That's the whole point of the risk of startup. Also the reason for the explosion of interest. I'm not suggesting that Gemini will win, but they are in the space, at the beginning, unencumbered by old tech (as the larger institutions are) and are making overtures to the established order. We don't know where that will lead.
That's not to say that some of the technology they develop can't be repurposed for resale to other institutions, but a lot of others are already playing in the blockchain technology space and they don't have the burdens of trying to create and manage exchanges, ETFs, etc. for an "asset class" that is miniscule and heading in the wrong direction.