The issue I see with this is that it splits the forum. There will be people that never use discord. At best, now we have to monitor two sites. This was a problem during the last comic-con. I never looked at discord. Some posts made on this site weren't seen until later. I don't understand why making and reading posts on this website is so slow that we need discord. Messages show up instantly. It's quite common to have a real time dialog using posts.
May I suggest that instead of disposing of the chatbox, that it be re-implemented using discord as it's back end. It's possible to embed a discord discussion onto a page. That way, this site can still be the common place for all friends to meet.