The Obi-Wan trilogy would actually be three films largely independent from one another.
Cinelinx is reporting that Disney is working on ideas for three Star Wars films that would focus on Obi-Wan Kenobi, all of which would be set between Episode III: Revenge of the Sith, and Episode IV: A New Hope. While the term "trilogy" is being tossed around with the project(s), the source of the rumor says the three films would be largely independent of one another, with as little connectivity bringing them together as possible (no three-film story arc here, it seems). This structure would be similar to how James Bond films exist, as each film's story operates in the same universe, with minimal meaningful overlap (post-SPECTRE, of course).
Also present in the films? Qui-Gon Jinn (in Jedi ghost form, I'm sure), Owen Lars, and a smattering of characters from the Clone Wars TV show. And the settings would include Tattooine for the first film, and to-be-determided other planets for films two and three.
Along with Star Wars VII, VIII, and IX, and the other confirmed spin-off projects in various stages of pre-production, this would bring the number of Star Wars films in various phases to about eight (my math: the numbered trilogy, two standalone films that presumably aren't Obi-Wan-related, and the three rumored Obi-Wan flicks). Three films for one character is quite the investment, especially with so many other projects on the horizon, but if anyone can pull it off, it's Obi-Wan (preferably played by Ewan McGregor).