She can't resign Eddie.
The Tories would almost certainly face calls for another election, and somehow I don't think they'd be so keen now!
It is, ironically, the rise in stock of Labour and Mr Corbyn, as well as the Brexit talks, which is keeping her in place for now, but both of those are likely to do for her eventually.
As for Brexit, it's probably about to commence a slow death. I think it's clear that a "Hard Brexit" (no single market, no customs union, no ECJ) will never get through this parliament (and even less likely, you'd think, a future one). "Soft" Brexit", where we stay in parts of the EU but have no say over it, would be hard to sell to the "loss of sovereignty" brigade. So that leaves the scenario Boris predicted at the very start (but hastily backtracked on) namely, we stay in a reformed EU.