I disagree with the theory / hope of the main parties that once Brexit has happened,
they can return to their cosy duopoly carve-up of power
Brexit means several years of negotiating with countries across the world, trying to regain the trade deals and markets that Brexit would have lost
It would seem endless
Meanwhile, the economy continues to roll downhill and standards of living fall for most ordinary people
After a Brexit crash, many angry voters will be looking for a party or parties to blame, politicians to string up
Either or both main parties could be permanently relegated to minor party status
It could be Labour, if JC continues to ignore the 70-80% of members and voters who are Remainers,
so they go elsewhere, permanently
It could be the Tories, if their angry 80% of fanatical No Dealers decide the crash is because Brexit wasn't sufficiently pure and needs more benefit bashing & immigrant-bashing.
They have a replacement party ready and waiting to their right
It could be both