Apparently the rights to the movie were hotly contested by a number of huge studios, with Sony winning out. It's expected that Sony will foot the bill on what is expected to be a lavish production.
The default position, when these things are announced, is usually cynicism - you have to protect yourself after years and years of terrible adaptations, but perhaps Assassin's Creed is the kind of IP that would work well as a movie. There are plenty of interesting themes running through the narrative.
Maybe it'll be like a modern day Highlander, with a modern day story interspersed with dalliances into different points in history. Yes... please. Make that movie!
There can only be one.