It's too early to tell the political fallout from all of this, but there is certainly potential for disaster--the public thinking it was all the Republicans' fault, and the Republican base being so disgusted with the "solution" that they stay home in large numbers on election day. I don't think there is any chance of the Democrats getting to 70 senators--I think there are 21 Republican-held Senate seats up for election, and the Republicans will probably lose at least a few. I'd say the worst-case scenario is losing about half of them--some are in heavily Republican states. But the magic number is 60--once the Democrats get to that number they can do just about anything they want, if they have the White House too.
Currently the Republicans have 49 Senate seats, so they'd have to lose all their seats that are up this election for the 'Rats to get to 70.