There's currently a dozen other Twitter ish platforms out there. If twitter got too annoying, it'd become the next Myspace in a matter of weeks. The Market Share of Damocles is ever present.
Yes, I agree, but with a caveat.
1. The "next big thing" tends to be fueled and aided by the mainstream media and popular culture, which has it's nominal left-bias on the political grid.
2. The odds are that the "next big thing" will be created by someone from or similar to the "silicon valley" mindset, and it's nominal left-bias.
So in other words, should Twitter or Facebook fall, barring an early period of it's "Wild West Days", and assuming the center-libertarian-right side of things be able to jump on it and make use of it faster and father than the left does... it'll just be a case of "meet the new boss, same as the old boss" pretty quickly.
For every Drudge Report, there seems to be ten Twitters, Facebooks, Googles etc. And there seems to be a trend for the new platforms to become ever more symbolic, visual, and brief. And it's easy to meme-out some sort of leftist Robin Hood rhetoric, and not always as easy to meme-out a counter argument of "Yeah... that's theft", "Yeah, that's being generous with other people's money." "Yeah, that's just going to make things worse in the long run..."