I'm not saying that people *will* change their minds. I'm just saying that there's not really any reason to do so *now*. It's a very bold person who commits themselves to one opinion for all time, even in the face of circumstances that may very change drastically... Still, to each their own. I doubt I'll ever change my mind either, if it comes to that, but I at least *might* if Brexit works out, the EU fails etc etc etc.
(For the record to those who can't access the link, the two-thirds figure quoted comes from taking all people who support Leave (45%) and adding to that the 23% of people who voted Remain but believe that Brexit should now happen as a result of the referendum; the remainder is split between 9% "don't knows" and 22% of people who would rather the referendum result were overturned; hence only half of Remainers now support Leaving by the Telegraph's definition. Also it should be acknowledged that YouGov, the source of this poll, put things in the same language, so this isn't the Telegraph attempting to mislead per se.
See also
https://d25d2506sfb94s.cloudfront.net/cumulus_uploads/document/l094qb1ds4/InternalResults_170508_Releavers_W.pdf . There's some amusement to be had from the second and third columns in particular.)