Aksai
the complaints about the border over the years have come from the people of Gibraltar when the Spanish enforce border controls on their side. I've never heard of the Gib. authorities trying to stop Spaniards from nearby areas from visitng/using Gib. and it always looks as if they'd be very happy to have an open border (it would really help the cigarette smuggling business but that's another argument).
I am not advocating handing Gib over to the Spanish - what I'm suggesting is that in the very long run it will probably occur to the people of Gibraltar that they'd be better off in Spain than out of it (imagine the UK -or at least England - leaves the EU for example...)
Might well be 100 years time