I'd have thought that when the HoC resumes today they should pass a new bill to force Johnson to request an A50 extension immediately, and if he refuses it seems the Scottish Court of Session have the power to do it for him - it seems pointless to think that in less than 3 weeks the EU will bend over backwards to help this particular PM and failing government whose days are, hopefully, numbered.
I'd prefer to see another referendum before a GE since knowing what the electorate currently think would be useful, since I think the oft repeated mantra beloved by Brexit enthusiasts along the lines of 'the people want out now' needs to be sanity checked, and at least that way there would be a result that would inform any subsequent GE since I suspect, and hope, Brexit would be off the table, and if not then that there is still a majority support for Brexit it would have been confirmed.
No matter what it will be a can of worms.