My guess is that WotC is going to just use the existing studio as a starting point on which to build up a new studio including with some well-known people. The studio currently only has 55 employees, nowhere near enough to make a true AAA game. I expect it will be expanding immensely over the next few months. WotC has long wanted an in-house videogame studio to make D&D games so that it could avoid the ugly and unhappy situation they had with Atari for many years. I guess they finally have that with this acquisition.
Tuque Studios released 1 game previous to this, which got good reviews and was a moderately successful game, which got published by perfect world.
It's surprising enough that a company with so little name recognition and only one game under it's belt, was able to land a D&D licence, but to do so well, that WotC was excited enough to buy the company says something about the product. If WotC had bought them from the beginning, that would be different, although I doubt Canada would have been their first choice of location to buy a video game company. No I suspect this was motivated by a prototype of the D&D game that Tuque Studios is doing. Which tells me it's going to be good.