When Corbyn is re-elected leader (as he will be) the centrist Labour MP's will have to consider whether they split off. My prediction is that while those discussions are going on they will resign the Labour whip en masse. They will have little to lose because they will be de-selected before 2020 in any event. That will leave Corbyn leading a rump of about 30 MP's with the SNP having 56. SNP will be declared HM Opposition. Please note this is not necessarily what I am advocating - just a prediction of what might happen.
There'll be very few leaving the labour whip , When Corbyn is re-elected the vast majority of opposition will subside ,they won't risk their seats. The top rebels will either put up or shut up IMO. They know a split sends them into obscurity . The party have been led into light brigade charges by the minority MPs too many times . Corbyn has been shown the support he has behind him and that's why he didn't quit when the MPs and media lapdogs thought they had him cornered with the relentless coverage making out he had an hopeless case. Not only will he retain the leadership he will be in a very strong position to fight off this one-sided Austerity to come from the Tories to protect their lobbyists from the fallout of Brexit. That's when the electorate will see what is behind this Tory right wing influenced shower are about.
Don't get me wrong Marlon, if I thought any of what you say would happen - I'd be up for it. It won't.