short term pain for long term (potential) gain... I suspect the redrawing of the boundries and reduction in total MP numbers will ignite the whole de-selection stuff again and that will probably come after what I fully expect to be a fragmented and toxic conference - I honestly think a split will happen fairly soon - unless May decides she wants to take advantage of the mess labour are in now and call a snap election to ensure she gets 5 years to formulate and execute a brexit strategy and she does so with more perceived legitimacy
In what sense? We'd be talking about a completely new, fresh political party here. I'd imagine there's a lot of work involved in establishing that - even basic elements like leadership elections, party meetings, how they're organised/structured etc.
I'd imagine a Corbyn/anti-Corbyn split would drive the vote down the middle. Corbyn would keep the leftist element, but would still retain a lot of support due to having the party name and a lot of people still voting Labour irrespective of what happens. So in that regard, a completely new party would perhaps have somewhere around 15-20%, depending on how well they pitch themselves/their manifesto etc.
The problem would come to winning seats. The Labour split would drive a lot of constituencies down the middle, potentially allowing the Tories to gain in a lot of them. It's a complete Tory wet dream, actually - a divided Labour vote giving them many more seats. I'd see either Labour side struggling to take more than 100 seats.
And what happens if it's shit, too? What if the leader is absolutely terrible and doesn't reflect the aims of this new party? Do they split again? A couple of bad elections for this new party and it'd have the potential for utter disaster - they wouldn't have the comfort Labour have in certain areas no matter how poorly they do, and would lack the structure that comes with longevity to keep going. Yeah, there's a voter base, but that's no guarantee of anything...look at UKIP, who have lots of voters, but risk disaster if they don't find a good new leader because the party is still bare structurally.
I understand the reasoning for a Labour split and in a PR system it makes complete sense. But in the current context it'd be a disaster and would perpetrate massive Tory gains...the thing that the moderates supposedly want to stop. It's the same as the ideological purity that Corbyn's being blamed for, only in a different form.