In terms of the original question, I'd wonder the reverse really. I don't think Juncker's speech will do anything to push people one way or the other -- it was irritating but I want to be a member of the EU on principles that aren't necessarily affected by who is the present leader (rather like I wouldn't up and leave the UK if the present PM were incompetent (hypothetically)). Probably will just serve to harden views that already existed.
Most polls seem to suggest that views haven't really changed much at all since the 2016 referendum, and in practice I think that's likely to remain the case for another couple of years. "Regrexit", if there's ever a thing, would presumably only start to kick in some years down the line assuming that the UK didn't get a good deal and started suffering as a result -- and probably not even then.
The main factor will probably be apathy, or perhaps some lack of belief that the vote will make a difference. There are sound democratic reasons why we might hold a second referendum, but it's hard work to persuade people that it's anything other than a cynical attempt to reject the result in 2016*, so maybe the less strongly-committed Leave voters might just not turn up, allowing Remain an easy win by default.
Well, possibly. I
*I mean, obviously it's also exactly that cynical for some people, but I do think you can legitimately defend a second referendum even if you wanted to Leave the EU in the first place, just as long as the question is different, and the consequences of a vote against whatever's proposed, presumably the "deal", would still result in leaving the EU.