The early signs are here. One of the major tools that the GOP uses to discipline its caucus is the threat of a primary challenge financed by (say) the Club for Growth. Well, now the Democrats are starting to do the same thing, financing primary challenges via Act Blue. Blanche Lincoln, a very conservative Democrat, is now facing a very serious challenge from Bill Halter. Halter is openly running at Lincoln from the left.
It will be important to realize that parliamentarization doesn't necessarily mean radicalization. Support for the Afghan War or nuclear power could easily remain in the party platform. Similarly, the parliamentary GOP could move back towards the center. But parliamentarization does mean increasing party discipline ... and an ever-decreasing importance of the individual versus the party.
No, one vote by Senator Scott Brown for a teeny tiny $15 billion jobs bill, quite literally watered down by an order of magnitude from what the President initially suggested, does not count as rebellion. Vote the letter, not the person.