Sorry John, but the way Momentum are taking over the Labour party, it's going to be a long time before they get elected again. Theresa May is going to have to screw up really big time before the general public will accept Corbyn. Now if he were to resign (highly unlikely) and a moderate took over, then they would become easily electable, but Momentum won't allow a moderate in, so Labour will stay out in the cold. Things were different when the last bunch of disaffected Labour politicans jumped ship, and helped form the SDP, but whilst the current bunch are making noises, none of them have the backbone of the older bunch.