It would seem we'll be relegated to running random as FC only. With the upcoming removal of Vengenace from player attacks we should expect to get stuck at around 4 - 5k dps dummy-style.
The main problem with the change is that we won't even be theoretically able to defend our healer as splash damage doesn't increase our own damage output.
Long gone will be the days when we poured out damage as a result of unskilled players attacking us in groups and allowing our healer to concentrate on healing like there was no tomorrow.
The primary change to battlegrounds should be FC lasting much shorter. If noone wants to come as a tank, then a squishy will have to do the job. In all likelyhood we'll see more healers running with flags as they're the only ones who have a decent chance to survive the onslaught.
As for those of us who tanked our way through BG:s. It's either respeccing dps, and getting that big two-hander, or hoping that at least pets still give us Vengenace. Some taunting should give us the answer post-patch.