By and large i think this is spot on indeed. May's key concern now (especially as she is not standing in the next GE) is legacy. She has a very short time left. She cannot be the PM to have destroyed the Tory party (also apparently her core driving force has even before brexit been a case of Party and its unity), nor can she be the PM who was 'held hostage' by either side (adding to what reportedly is already a stubborn nature), she also cannot be the PM who wavered on 'her' (key part here) plan on brexit. Particularly as she has reneged on nearly all of her domestic promises to the point where Universal Credit (which has been a disaster thus far- and ironically costs the tax payer far more than the older system) has been consistently pushed out, despite experts, those on it, charity groups and her own MP's trying to delay or revamp it. Its literally only mounting pressure that has seen her add changes to it- much like brexit. She technically 'breaks' rather than bends- her famous U-turns, are not her bending at all, but a break- seen with the fact that each time, she doesn't re-engage with the policy, but leaves it in ruins and goes back to 'status-quo'.
Its also the wider issue with Brexit. It was always a Conservative party project, and here's the thing as we've indeed seen over the past few days, and last year- She is unwilling to make brexit cross-party as that would rip the Conservative party apart. There was never any hope of brexit not being essentially under the thumb of the Conservatives and i would argue that is exactly why brexit is not, and cannot be 'sustainable' given this fact and the referendums result. It was always going to be 'party politics'.
Which is why we've had a divide UK while ironically a relatively united EU. As i mentioned the process of this Conservative managed brexit- its Britain's biggest political failure since Suez.