City have a better squad, but they don't have a functional first eleven. Liverpool are defensively suspect. Arsenal just know how to beat the inferior sides, that's why they always finish in the top four.
They scored late against Leicester last season and it meant f all in terms of the title. Hence why I said you'd think they would push on....but they never learn from past errors.
They got lucky today but they tend to run out of steam in March and April, so Chelsea shouldn't worry. But given the circumstances (Wenger's last season, contract sagas), it may work to their advantage.
I actually think Chelsea could be clawed back....it may all depend on the Anfield game.