1) The tea parties throw up their hands, abandon the struggle as futile, and go home.
2) Tea partiers start working on a third-party challenge, identifying a leader or a few leaders, and begin coalescing into a visibly organized force.
3) Tea parties infiltrate low-level politics, concentrating on County and State offices and getting aware and knowledgeable people into election commissions and the Party hierarchies, concentrating on Republicans.
These are of course pure absolutes, and pure absolutes don’t occur in Nature; the actual result will be some mixture of the above. Simplisme is useful as a one-sigma estimating tool, though.
Alternative One is admission and acceptance of defeat. Nothing changes in any substantive way. The new Republican-led House of Representatives falls into the McCain Trap, accepting “compromise” that really means Cooperate with the Democrats and they’ll let you have pork and corner offices, invite you to Beltway cocktail parties, and get the New York Times to say nice things about you. The only part of that promise Democrats will keep is the pork and the nice offices, of course. Result: the 2012 elections repeat 2008, only this time there are no Blue Dogs, and the Republican Party disappears for all practical purposes.
Alternative Two is the classic response. In the face of Power, build an opposing power structure; it is the fundamental theory behind labor Unions, which ought to give you a clue as to how that works out. The new leaders will be vulnerable to Alinsky-like tactics, the Media will be in full-throated opposition, and Establishment Republicans will be jealously defending their turf. Result: two weak forces opposing a powerful one, and unable to ally with one another. Raucous contention is the order of the day, while Democrats smugly consolidate their power structure. B. Obama carries all 50 States in 2012.
Alternative Three has a hope of success. But it’s boring.