You are probably right, the remainders / reversers are still thinking in a mindset of we didn’t lose by much, the lies like £350 million were so blatant and the impact of social media and the stark demographic differences in voting patterns means they are in an environment were almost everyone they interact with agrees with them.
So we somehow get to a second referendum and we only have to move the vote a little to get to 51:49 win and we stay and everything is OK.
The problem is as you say 51:49 isn’t good enough. 1975 at 65:35 still has Labour going into an election in 1983 with a pledge to get out, Jimmy Goldsmith is financing the referendum Party by the 90's and then there is UKIP who would love to run on a narrative of establishment betrayal.
It will take unbelievable change to get a UK signed up to the European project, with Trump who knows what might happen, at present the Brexiteers are assuming a great and quick trade deal with the US will help them, but Trump is so unpredictable he could do something that has the opposite effect.
Likewise inside EU the debate has simply moved on, an EU with united foreign policy and a defence component was held back by the U.K. moves are already being made on the assumption the U.K. Will simply be gone in 2019. All bets are off if Le Pen, Wilders, 5*, and AfD win in 2017, but it is perfectly possible the establishment will remain in charge and so at least some will be in two minds about letting an unreconciled Britain back into the club. Paul Nuttall being interviewed the other day and when it got to difficult issues simply confidently predicted the entire EU WILL collapse before we get to 2019. It is pretty risky to base your strategy on that.
Farrage, Nuttall and the ‘Bad Boys of Brexit’ don’t just want us out they want to destroy the whole concept of an EU they want to burn it all down. They are whispering in Trumps ear in DC and if they are seen to be making progress will be seen as an existential threat in Paris and Berlin, at that point compromise EEA is not an option, EU will force WTO or come back to full membership.
I can see a second referendum happening, I can see a realignment of British politics happening which would allow it, but I can not see it by 2019. We will then have the 2020's with us going in the opposite direction and pulling away from a 40 year relationship while the EU will either collapse because of the contradictions of the Euro, or develop further and faster in a federal direction without the UK there to hold it back.
By the time the British public are ready to consider maybe we made a mistake, the EU of 2016 and especially our half in half out status of no Euro, no Schengen rebate on contributions will be long gone.