Good for Johnson and perhaps Swinson if he stays where he is. If the rumours about his health have any credence he might go, and his support from the grassroots, especially on Brexit (Labour members rather than voters) is fading fast. But he’s not very savvy and the health of the Labour Party, as opposed to pushing his own, outdated, agenda, has never been his top concern, he’s spent most of his career at odds with whoever the party leadership were.
Johnson might be more concerned about Farage, will be interesting to see what he campaigns on, might have to be no deal Brexit to negate the Brexit Party. Fun times.
He's painted himself into a corner, and would have to campaign for a no deal Brexit. Which is why he would lose.