Rendon will be fine as he ages. As long as his shoulder holds, he will be fine in the field. 3rd base is a flashy position but it doesn’t require that much range. It’s why ARod and Ripken played there late into their careers. (PEDs may have contributed to both also)
Mike Schmidt is another.
I would be way more worried about giving the money to Strasburg than Rendon but we have Scherzer as a good case.