Based on some of the spoilers that I have read, I think that Blair will choose Dan, but he and Serena may reconnect also. This is what may "derail" SB's relationship. If that is true, does that mean that in Season 6 we will have a new triangle - Dan, Blair and Serena? I hope not, because I want Chuck and Blair to get back together. They've been apart for too long!!!
I want Chuck and Blair to get back together, but I'm not sure that I want them to get engaged yet. I mean Blair has been deluding herself into believing that she is in love with Dan, so I don't want her to just turn around now, so quickly, and accept Chuck's proposal ( if he proposes). I would prefer her to take some time to reflect and to get Dan completely out of her system. I don't want her confused or conflicted in any way when she chooses Chuck ( which she will do eventually). I want her whole heart to belong to him. No part of it should belong to another man.