I'm not sure. Right now as a lvl 36 fem Mage/Vamp with only a couple of Vamp perks left to fill, it seems Dawnguard waits for me at places I go to get a "Word of Power". So, I've gotten so I fast travel to a nearby place I've cleared, and Serana and I ambush them. I like the fast travel, mainly for time, and the quickest way from point A to B. I can't get rid of Serana and get Lydia back, so I'm stuck with her, for the time being.
If another patch was put in eliminating the fast travel, I doubt I'd get it. I mean, I can't even use/ get a horse as my "companion" can't either. Even more so, I have to supply her gear anyway, so let's keep the fast travel?