We may be witnessing proper tactical voting working in England as it did in Scotland prior to the SNP gaining supremacy. The soft left, who would include myself and other former Conservative voters of a similar mindset, will vote for those most likely to gain a seat. But having electable candidates is a prerequisite for that to happen.To a point I agree, and yet...
... for me, the first significance is that Labour appears to have completely lost control of the two demographics that swept it to power in 1997; the soft-left and the old industrial heartlands (who whilst not particularly keen on Blair, at that point were still fundamentally loyal to the Red Rosette). Despite this, I'm certain that the hard left who control the Labour Party machine will cling to their broken ideology, convinced that they are right, the voters are wrong and that their day will come.
...the second is that this significant victory has shown the centre-left that by ruthlessly getting behind one of the two left-of-centre parties, they can defeat the Tories, by dividing the vote, they can't. Unless Starmer can get a grip of his hard left (doubtful), I could see a wholesale switch of the soft left vote to the Lib Dems. This in turn may encourage some on the Tory left to desert. However, as I note above, the price the Lib Dems will have to pay for this will be ditching their wackier policies.