That's literally what it is. It's what any vote is. The polls were all over the shop in the months leading up to the vote.
https://ig.ft.com/sites/brexit-polling/
Had the vote been a few months before the result may well have been different. If they had another vote now it might be. It's a pretty flimsy mandate for a permanent constitutional change. The fact that other changes have been made without any vote doesn't change that.
The point about the impact of staying in is an interesting one, I guess my biggest problem is that there was no plan from either side about what us being out of the EU actually means so are we going to get another vote when they decide what it means? I guess not. It is a bit like Wenger Out, the obvious follow-up question is "who in?" and I've seen you argue that it doesn't matter, at least it will be different. I don't think that's a very helpful way of thinking, you have to have some plan that will take us forward and with the EU there hasn't been one and still isn't.