But the boundary changes are going to mean there has to be a reselection process in an awful lot of constituencies.
This website appears to show the proposed changes that were going to be made back in the last Parliament (blocked in the end by the Lib Dems). What happens now is likely to be reasonably similar. If you look at, say, Vauxhall and Streatham constituencies you will see they are completely utterly redrawn under the previous proposals and will clearly have to be recontested This gives a once in a generation chance for the left of Labour to shaft Blairite MPs and can happen whether Corbyn and the leadership want it to or not.