Starmer can survive losing Hartlepool, after all Corbyn, despite winning the argument, lost Bishop Auckland, Blyth Valley, Darlington, NW Durham, Redcar, Sedgefield, & Stockton South.
I don't think Starmer can survive losing Hartlepool and Batley & Spen
What might save Starmer is Scotland's result overshadows everything else
Despite the PM's bluster there's legal action likely to follow and that might be R (Miller) v The Prime Minister and Cherry v Advocate General for Scotland on steroids.