What are the odds that congress will be able to repeal Obamacare?

Very slim to none. First, the republicans would need 60 votes in the senate, which would require 13 democrats, and few of them need to worry about reelection. In the house, most of the democrats who would vote for repeal (the blue dogs) got wiped out in the last election, as evidenced by Nancy Pelosi's sweep in the leadership election. Like it or not, for now the quest for repeal is mostly symbolism to keep the base happy. To really repeal the republicans need the senate and presidency.