If the Winklevoss ETF doesn't come out int the USA, a different one will come out somewhere else eventually. It's inevitable.
There is at least one European-listed ETF effort I'm aware of, which already has a few million USD in the kitty and was looking for additional investors at the London event.
If the USA wishes to keep shooting itself in the foot via excessive regulation of the Bitcoin space, so be it. The rest of the world will take up the slack.
There is already a Bitcoin ETF, from Exante in Malta.
The US government has no reason to try to stop the twins. In fact, it provides the US government more avenues of leverage to do what they will, as well as an additional tax base. There is only win for the US gov, no lose here.