I was never waitlisted, so I learned little about it. I don't know if the waitlist tends to move this late in a cycle. Hopefully someone more knowledgeable will chime in. Obviously, it's getting pretty close to the semester. Based upon your June 14th posts, the resident waitlist has stayed still all summer. Anything could happen — someone could change their mind — but the odds seem kinda long at this point.
What do you mean by "nixing your hopes"? Are you asking whether you should emotionally prepare for rejection? If so, the answer is probably yes, but it doesn't matter that much. Rejection can be really hard, but barring some sort of mental illness or other factor, I'm sure you'll get through it. If you're asking about whether you should take practical steps to give up on Dal and go to UNB, then that's a little different.
I guess a couple of questions come to mind. First, do you actually want to go to UNB? Or rather, would you be okay going there? If you wouldn't for some specific reason (e.g., you have a significant other / family who you don’t want to leave, you’d suffer undue financial hardship, you have a horrible fear of rivers but not oceans, etc.), then well, maybe you have your answer. Otherwise, I think UNB will probably give you a fine legal education. Plus, it’s cheaper than Dal.
Second, if you’d be ok moving to Fredericton, then do you have a place to live there (with utilities and everything set-up)? If not, then it’s getting pretty late. Provided you want to go to law school this year (as opposed to waiting and maybe needing to reapply to Dal next cycle), then yeah, you should probably be preparing to move. If you haven’t already, take all the practical steps involved in going away for school.
Sorry, I can’t provide more insight on the waitlist itself. Good luck.