Dave,
I wish had that crystal ball that could tell me with such absolute certainty what leaving the EU will and will not affect.

There are no such things Dave.
Can you suggest a chain of circumstances that would lead from Brexit to a tightening of regulations on refugees and asylum seekers none of whom originate in EU?

At a push I could produce a link from Remaining to such an outcome, but it would still be fantasy.

You appear to be the only person on Earth suggesting that it is a Brexit issue. That makes me think that this is just another of your vacuous whims with no basis in reality.