He's honestly been the most consistent starter this year. Not only that but his peripherals show that he has been even better than his ERA.
Extend him and as long as Sandoval and Suarez keeps pitching well the starting rotation should be set for this year and next between Ohtani, Cobb, Sandoval, Suarez, Heaney, and Barria/CRod.
And then Detmers taking Heaney's spot next year.