So republicans purposely collapsed their party support by 20-40% to make a political point to the public, who already know they oppose Obamacare? I'm gonna disagree on that bro. I think they did this because they thought Obama would cave, and they thought the people would support them. Meanwhile Boehner and leadership knew it wouldn't work, but had little choice but to appease the crazy folks for a bit. At one point it seemed like they just might get some concessions, but that NBC/WSJ poll pretty much ended the farce.
Moreover, I think those tea party members in gerrymandered districts genuinely don't give a shit about national views that don't line up with their district. Remember in Game Change when Palin kept obsessing over her poll numbers in Alaska, a solid red state, and demanded the McCain camp run polls in Wasilla? That's basically what's going on here. If you're a congressman in lily white Howell, Michigan, you don't give a shit what people in Detroit think of you, or what people in the rest of the country think either. Your focus is on opposing Obama, fucking over people in Detroit whenever possible, and voting a million times to repeal a bill that can't be repealed. That's why these people were sent to congress.
Democrats are currently leading the congressional generic ballots by 8 to 10 points; that's election wave territory. Obviously that will not hold through next year, but republicans just took a completely unnecessary loss and achieved absolutely nothing but making themselves look insane. Only 25% of seniors support their actions right now.
Basically if Obamacare turns out decent and the economy continues to slowly recover, dems will do fine next year. If Obamacare fails and the economy stalls, democrats will do poorly. I think many people believed republicans were crazy before the shutdown, so I'm not convinced it alone will lead to any gains. But it sure as hell doesn't help republicans.