Bigmartin - The alternative to Mr Johnson was Momentum Labour lead by Mr Corbyn and
Mr McDonnell

And the electorate made their choice.

The Guardian which is often quoted by Labour supporters explains why to some small degree

https://www.theguardian.com/politics/2019/dec/13/five-reasons-why-labour-lost-the-election

If Johnson leaves or is sacked from being PM that won’t see the demise of the Tory party as there are now a multitude of others ,now with a much higher public persona thanks to the media coverage of the pandemic.

I would suspect that the electorate being as fickle as we are will forget all the negatives that have happened once we are through the immediate pandemic and Brexit negotiations.

Also Labour now thankfully looking to become less radical and more moderate having seen Momentum Labour isn’t wanted by the masses will following a few more re-shuffles by Sir Kier have an effective elector able opposition.