There really have been a lot of changes. Xander has talents and attitudes that he has effectively hidden from the Scoobies and which only Angel really recognizes (hense Xander hanging up on Angel instead of hearing the same lecture about allowing vampire memories to rule him). I don't know if there will be threesome action any time soon, but in this universe, it has happened before and it just might happen again. I think the stumbling block will be Angel who really doesn't feel comfortable enough with himself or these two boys to do it. And the stuff at the mansion probably isn't helping that.