Tactically speaking, the first thing that comes to mind is that Tauren Priests will have a defensive mechanism for anyone close by them. The War Stomp will be enough to stun and stall pesky players (such as Rogues) long enough for them to get clear or wait for reinforcements. If that is not enough, the base health increase allows them to survive a little bit longer. They will probably survive an extra 2 seconds before they get turned into beef. Priests and Herbalism also go well together about runescape gold. I am not quite sure how handy Nature Resistance is going to be. My first thought is that it will increase their survivability against Chain Lightning and other related nature spells that are prominent in Ulduar to get RS gold.
Here is another one over which the player base seems to be split in half. I mean, not to put too fine a point on it, but it is not as if there is no precedent for trolls turning into animals. Seriously. In Zulaman and Zulgurub as well as Zuldrak, we have seen Trolls channel animal Loa to gain power. It is certain possible that certain Troll Priests could call on their Loa for similar empowerment, and thereby gain Druid-like powers. They have the pick of the pack in terms of animals to worship. What is really intriguing to me is which set of Loa player-character Troll Druids might call upon. As Darkspears originally hail from Stranglethorn, they might call upon the jungle Loa of Zulgrub about runescape gold, assuming they are now freed from the influence of Hakkar. On the other hand, Zulaman offers more immediate analogues to current Druid forms, including Bear, Cat, and Bird Loas to get RS gold.
For me, the Stranglethorn bunch seems much more likely, actually. If you have ever quested in Zabrajin, you do some scouting on Lost One Druids in Feralfen Village for the Troll Shaman Seer Janidi, and she says, "No self-respecting Darkspear troll engages in bird worship. Their spirits are weak, capricious, and best left to the Amani."