I think the only way he'll opt in is if he pitches poorly the rest of the way. If he's worth keeping, then they'll most likely have to extend him. f he doesn't do well, then I don't want him.
I want them to attempt to be reasonably competitive next year. To do so, they will need sign at least one good starter from a strong free agent crop this off-season. If Rodriguez pitches well, they have the inside track to sign him before he becomes a free agent. That might be their best chance.