I’m not sure the Labour right will jump. The prospects for a new centrist party are pretty grim. The Blairite model was of a small professional party drawn from the middle-class, backed by close links to mass media and a healthy advertising budget using corporate cash.
There’s a number of social changes that work against this. Rising inequality means there just aren’t the same numbers of middle-class professionals who retain the social-progressive views of their student days but are comfortable enough economically to fear Labour Left “Marxism”
More importantly the decline of mass media means you can’t just buy votes through television like the old days: you need an activist base to drive support online and on the street. Labour moderates don’t have one (and don’t want one), traditionally they just borrowed the Left’s during election time and packed it away in the attic the rest of the time.
So they’ll hang on and assume their CLPs will, come Election Day, sigh and roll up to elect them because “we need kick out the Tories”, then presumably have another crack at deposing Corbyn once he’s PM.