"April, May: June."
Was the best summary I've seen.
The polls make this look like a sensible (if u-turney) move. But there's a lot that can happen in 7 weeks.
Tory MPs in remain areas are at high risk. In addition Tory MPs who scraped a win at the last election (South West in particular). Lib Dems could win 30-50 seats if they get their act together consistently (and that seems likely).
Tories are hoping for Labour to collapse, and whilst that looks likely, it's one thing polling a disillusioned lifetime-Labour voter outside of the election cycle, and what they do when pencil comes to paper at an election. Assuming that Labour actually work together now this has been dumped on them (instead of sniping at Corbyn until he is unseated), maybe they could limit damages. Never mind UKIP's zombie corpse taking critical votes from the Tories (and Labour in some areas).
So 50 SNP, 50 Lib Dem, 200 Labour, some others - enough to mean May could have a majority that isn't that dissimilar to now - i.e., all for nowt, and it would look pretty bad for her.
But she'll dodge the election fraud by-elections.