Something I was thinking about. First, I apologize if this idea has already been discussed somewhere. In Starcraft 1, in the Protoss Campaign, there were the Judicators who fought against Tassadar's troops who defended the Dark Templars. There were missions where there were battles between Protoss vs Protoss. In Brood War, in the Protoss Campaign, there were some Protoss who defended Aldaris (a Judicator) against us, the Protoss who defended Kerrigan's cause. Well now in Starcraft 2 every Protoss work and fight together against their same enemy : the Zerg who destroyed Aiur, their planet. And they will fight against Kerrigan. Now there are no more fights and hate between the original Protoss and the Dark Templars. So I wonder : will there be wars between the Protoss in SC2 ? Of course in multiplayer indeed. But in the solo Campaign ? The Protoss will not longer fight against Mengsk and Raynor, they are their allied. Now there will be the hybrids, and the arrival of the Xel'Naga. So maybe some Protoss clans will try to defend their creators, and others will try to annihilate them once for all. So there will be wars between the Protoss. What do you think about that ?
Oh, but there is contention, and much of it. The Dark Templar want to wait a bit, build up their numbers and supplies to retake Aiur. The High Templar want to do it now. The leaders (Zeratul and Artanis) are getting along just fine, as Artanis sees it Zeratul's way, but it is totally and completely against the mind set of the prideful High Templar, most especially the zealots.
I don't think Protoss will try to defend Xel'Naga considering in what state Zeratul came to Raynor to tell him about them. Though he might have just been beaten by Kerrigan, I think the Creators are behind it
There would have to be some battles between Protoss. It would make some interesting gameplay. Other then that, like Samir Souleyman says, there will of course be some clans of Protoss who might have different feelings about some stuff that has happened over the past years. And it seems that Blizzard likes to let "allied" races fight each other, just look at Warcraft: Frozen Throne. In the Orc bonus campaign you still had to fight humans. There should be some Starcraft examples to, but it has been to long since I've played the Starcraft single player to remember very well.
Well they have been separated for around a millennium by taboo and fear and with the rigidity of Templar society it won't change in just a few years. I think the Templar and Dark Templar merely tolerate each other for mutual survival and am sure there are small skirmishes here and there by Templar rebels who want to retake Air NOW and a few Dark Templar on a vendetta against the Templar
I'm sure there will be Protoss vs Protoss in the campaign, especially with Ulrezaj still running around. I remember reading that he'll be playing a role in SC2, and if this is true he'll most likely be leading some renegade Dark Templar in a sabotage campaign against the High Templar. This will eventually lead to even more contention between the two castes, and possibly even into open war. Unless I'm wrong about Ulrezaj even being in SC2... I have a habit of remembering things wrong
I really want to see at the end of SC2 the protoss united against the terran dominion, i want to see both sides completely united and the protoss should be as strong as they ever where, take back Aiur give us that great battle!, with the new bigger map size and unit amount for that size as well for that size two bases you start out with, I live for Aiur!