The writing is already on the wall, I'm pretty sure. I'm going to go out on a limb here: I
seriously doubt the Time Lords will be back permanently.
Tenant once said (I'm pretty sure it was at ComicCon) that his final episode would touch on the Time War, at least as much as the series ever would. The spoiler clips had the Time Lords clearly stating that they were at the outermost edge of time in the Time War, and that this was the final day of the War.
Also remember that Nine and Ten pretty much definitively stated he himself had ended the Time War and that there were now no Time Lords left. That and the line about the Doctor using "the moment" to kill Daleks and Time Lords makes it fairly clear to me that this is probably a part of the Time War that, somehow, escaped the time lock spoken of in Journey's End or else just broke free somehow.
In other words, I think it's a slice of the past come back to visit us, allowing the Doctor (and us) to visit the Time War.
And we've seen from the spoiler clip that these people are demoralized and pretty desperate and Dalton's character is either insanely driven or has been driven insane. In terms or morale (and moral corruption perhaps) at least, this last cell of Time Lords is pretty clearly on its last legs and they know the end is in sight.
To these Time Lords, the Time War-as far as they are concerned-is still going on. One even said that time was reviving Time Lords to find new ways for them to die.
And Dalton's character cheering, "For the end of time"? This is just my guess, but I think either he is talking about freezing the future to avoid the Time Lords' ultimate fate or destroying it altogether, taking the rest of the universe down with them as they go.
I think the Doctor is going to be forced to settle things, once and for all, but
again at the cost of this last remnant of his people-who are a shadow of what they once were-and his own tenth life.
But we'll see in a couple days if I'm right or not, won't we?
