Cole doesn't have many years left in him but then the argument should be, if age is such a detriment to his performance, others should have replaced him on merit. Whilst his work around the park isn't so great, I think the likes of M Vunipola show what folly it is to pick a player for the secondary attributes first at the cost of the primary one. Our complete inability to scrummage was the single largest contributor to our defeat in 2019, especially given how frequently we were knocking on that game. The lack of mobility in our props was not such an issue.
When Cole gets too old, other props should naturally be passing him on merit. As it is, our supply at tighthead has dried up for various reasons. Also, even though we are rebuilding, not every player needs to be swapped out at the same time for future prospects. Sometimes you should just pick some older, experienced players in good form even if you think you may replace them in 2 years time. That's fine, then hopefully when you replace them, the newer players now will have 2 years more experience and be settled.
I want to see the likes of Cole replaced as he is not the future for us but I want the argument to be "Cole should go because player X is clearly better" rather than "Cole should be replaced because he is old and player X might be better in the future." South Africa have had some of the bulkiest, least mobile props in the game for years and it doesn't seem to have harmed them. If the rest of the team is able to deal with the props being slightly less mobile then pick the ones that will do the primary role of props best. There is a reason that, over time, the preferred type of player in certain positions has tended towards certain body types and skillsets.
Mobile props and lineout flankers are my 2 pet peeves when it comes to picking players for the secondary characteristics first and practically ignoring what their primary role is.