Scotland will not have another referendum as the British government will correctly argue they just had a referendum were continued union won a landslide victory. And that the loser can’t cry do-over and demand a new election after losing. So the government will simply not permit another referendum to take place in Scotland for at least ten years have passed since the recent election on the question of secession.
The Canadian Supreme Court, too, ruled that the Quebecois couldn’t have another secession referendum too soon after the last one.
Northern Ireland surely will not secede as the Unionists have much greater popular support in Northern Ireland than the Republicans, and secession from the UK would effectively mean union with Catholic Ireland, something the Protestant majority of the province strongly opposes.