Interestingly enough, Obi-Wan Kenobi already plays a small, yet curious, role in the current Star Wars trilogy. If you listen closely during The Force Awakens, Obi-Wan is heard during Rey's Force vision, with Alec Guiness' iteration saying, "Rey!" and Ewan McGregor's iteration saying, "These are your first steps." This implies that he is directly or indirectly tied to the girl, and if that's the case, one would imagine such a tie would be alluded to or even play a direct part in his adventure. The soonest we could an Obi-Wan Kenobi movie released is in 2020, a year after Episode IX's release. That would be the prime time to hop on the project since Ewan McGregor would be just the right age to don the Jedi robes again.