972 Magazine collects an amalgam of polling asking Israelis about their support for withdrawal to 1967 lines (with agreed-upon swaps). Standing alone, withdrawal is close to break-even amongst Israeli Jews (add in Israeli Arabs, who of course also have a vote, seems to push the numbers up by about 2-3%). But that number rises if withdrawal is considered part of an all-encompassing peace agreement.
What do we glean from this? One answer is that, like Bibi, Israeli voters do view '67 borders as a concession -- one they're willing to make, but a substantial concession all the same, and one they expect other things in return for. Another answer, which I think is closer to the mark, is that the Israeli public is very leery about withdrawal actually accomplishing anything. The lesson of Gaza and Lebanon were that withdrawal is greeted not by peace but by rockets, rockets, and more rockets. What both those withdrawals have in common is that they did not come as part of any larger agreement -- Hamas obviously still doesn't recognize Israel, and Lebanon has been rather pugnacious in announcing it will be "last Arab country to make peace with Israel." (Incidentally, the comments to this post on how its Palestinian policy has affected the country's internal dynamics are really interesting).
Obviously, one could say a deal is worth no more than the paper it's written on. But even paper is worth more than no deal at all. At the very least, there is a considerable difference between making a deal and reneging on it, versus explicitly holding out that no deal had ever occurred.
In any event, I still am a little baffled as to what other basis for borders there could possibly be aside from 1967 lines. So I'd be shocked if any future agreement doesn't end up tracking the Green Line relatively closely.