Implants are permanent but removable if you should choose to remove it. I would recommend an implant to keep the tooth above it from protruding.
If root resorption tooth is asymptomatic , you don,t need to worry. No one can tell when the tooth will come out. Implant is a highly predictable and viable option for replacing missing tooth.once it is inserted and restored , it can service decades, no need to remove healthy implant.