Some might say that they're milking the franchise. I say - so what? Even when Episode IV came out decades ago, there were hints at a very large canvas of potential stories. Various comic books and TV shows have taken advantage of that, so why not some movies? The potential is there, so why not go for it?
Anyway, by the time you read this, it might already be confirmed, but one of the rumored anthology movies is one featuring Obi Wan Kenobi. If this is going to be reality, then it's safe to assume that Ewan McGregor, who played him in the prequel trilogy, will once again play the Jedi Master. For starters, it's likely that it would take place between the two trilogies, so he'd be the right age to play the part. Even more importantly, the actor himself stated that he'd be glad to do it again.
There is also a lot of potential for stories with this character. Twenty years pass between the two trilogies. Is he really just hanging out, snooping on Owen and Beru to make sure that they're being decent parents? How does he know so much about Sandpeople? Seems like he's probably had a confrontation or two with them there - perhaps we can learn a little bit more as to what they're all about. It's also possible that some other surviving Jedi have sought him out. Perhaps he had to go off world a time or two as there to deal with an impending threat? The galaxy is a big place, and lots of stuff seems to happen on Tatooine. And hey, is there any significance to the name "Ben"?
What's even more interesting is that in the upcoming Star Wars comic, they're going to be getting into some of those missing years of Obi Wan. In case you didn't know, it's all official canon now, and the movies and comics all share the same continuity (along with the novels and TV shows). I'm looking forward to that issue, but I doubt that it's going to cover all 20 years. Certainly there's room for many stories featuring that "old wizard".