Agreed, but if Corbyn wins the leadership I think there will be quite a long period when the right of the party will just stare into the headlights and fail to organise themselves at all.

Sure, they'll refuse shadow cabinet positions, and whine on a lot, but I don't think they're stupid enough to completely destroy the party. Or that they actually could destroy the party. The real split I think emerging is between the PLP and the Constituencies (the split with the Unions has been there for a very long time), and the Constituencies are taking advantage of the new democracy to force the PLP to address their concerns, their policies, ideologies and beliefs. It's not hard-left obviously, but it's definitely left. The great positive I can see coming out of a Corbyn leadership is that it could possibly move the overton window more to the left. That socialist ideas are not anachronistic.

A split between the parlimentary party and the branches/constituencies is not a new thing (the Tories have muddled on with the same split quite well after all through many years), but Labour has now given theirs power in the debate. Corbyns proposals are primarily to continue this approach into setting policy, from the membership up. I'm really, really looking forward to seeing the shape the next party conference takes if he is the Leader.

Although the question of the opposition being effective is a concern, it can't possibly be any less effective than it is now. Although I'm not sure about seeing Diane Abbot on a front bench again, she's an opportunist/careerist imo and I can't see her support of Corbyn as anything more than her glimpsing a possible shadow (and later a cabinet) position. What is at question is if Corbyn can hold onto the leadership going into the next election, because that would be interesting. I'd expect to see a much younger selection of candidates, and a large change in the makeup of the elected party if he did get that far. New New Labour.