My guess is that Scotland will seek Dominion status.
There could be a second referendum in 2017 but all the balls will have to line up for the SNP.
Corbyn will have to stay leader of the Labour party. I can not see labour being able to mount such an effective better together campaign. If he is replaced by another London MP as leader it will be slightly better but they will be portrayed as the London elite, as they were in the Brexit vote.
There will have to be bad economic news and the Scotish voters will have to believe that it is due to Brexit. The GDP of the EU is projected to go side ways for the next few years, this will have to stay the same. Brexiteers are giving the impression that trade deals can be negotiated quickly, so they will be judged. The relationship of May with Trump in negotiations, if nothing appears to be happening, could be damaging. I could see that May be lampooned as Trump's, Shih Tzus, only brought out in her leather trousers for a photo op.
The government will not have made any plans for an extra £350 million a week to be spent on the NHS.
The Scottish voters will have to believe that their views are being completely ignored on Brexit.