Jackson leaving Seattle to use the Harper Avery Foundation’s resources to fight for racial equity in medicine, April getting more resources for her own goals, and the little family unit more or less sticking together, is about the best way I can imagine Jesse Williams being written out without rushing anything.
Assuming Grey’s Anatomy doesn’t deliver just about the worst twist imaginable by killing him off in his farewell episode, Jackson will have gotten one last big episode with April and one episode to say his goodbyes to Grey Sloan, which is pretty great with or without a surprise appearance from Sarah Drew.