Can't see there being a GE just too risky for the Tories, and a new Tory leader seems increasingly unlikely anytime soon as would take 10-12 weeks to complete.
May will carry on but there are just roadblocks all around her. Maybe stay in the CU for whole of UK, get the DUP back onboard and hope for Labour votes
If the DUP vote down the Budget, we're in uncharted territory. Any PM that couldn't get his or her Budget passed would need to resign and a GE would be called BUT a) there's no constitutional reason to do this and May would be very reluctant to cause more chaos and b) the Fixed Term Act means there'd need to be two-thirds majority.
However, if DUP aren't going to play ball, the government is going to grind to standstill - nothing will get passed, yet no Tories will vote for a GE. It would be a complete mess (and the FTA is another one of Cameron's legacy; he really was a dreadful PM).
Because May knows this, she'll do anything to get the DUP onside and it looks like the whole of the UK will now stay in the CU, I'm not quite sure what that will mean for freedom of movement but it does look like the ERG aren't going to be happy in any case.