Will the remaining Dems support a override of Obama's veto of the repeal of Obamacare to stay in office n 2012?

I can't image so, even if it was a huge source of frustration, they already ped it, so those against it already want them out, and if they were to flip, those who may not exactly like it but like the idea would still support them. In short they have nothing to gain by repealing Obamacare.