Did this on my Trooper today and I'm very glad for the heads up because I have geared and relied on Jorgan quite a bit as super dps so I would've hated to lose him. I'm spec'd heals so losing Dorne doesn't hurt so much and may even provide a decent romance option, who knows?
As an aside, I was very underwhelmed by this end to Act 2. I won't spoil anything but especially compared to Act 1, this was a major letdown. Granted, the idea behind what's going on is epic and could've made for an epic story on TV or something but it was just very boring and felt like any other quest, imo.