Nothing will silence Johnson's inside-the-party Remainer critics like a big election win. If they pipe up now, he can have them sidelined or expelled, with no danger of losing power. It would be very different if his majority was just a few seats.
Brexit will happen, though on what terms is up to the EU. Maybe they should just finally accept it, because up to now, they've been trying to reverse it by making it as hard & slow a slog as possible.
Scotland is the danger for Johnson now. He'll probably have to just take a "hard no" stance to the SNP, as Spain is doing with Catalonia, and that's dangerous.
Corbyn already is on the way out as leader, though I don't blame him for what happened. The Brexit issue peeled away so much Labour support precisely where is usually was strongest, but that party has been a shambles ever since Blair threw its working-class principles in the trash. Corbyn spent more time defending himself against attacks from inside his own party than fighting the Conservatives.