Sounds like you’ve done the right analysis. If closing the card won’t significantly impact your average age of accounts or total credit capacity, I’d close it rather than taking a hard hit. Better to get a new card that will give a bonus and features you will actually use.
For many, though, a card that has a life of 20 years might be doing wonders for your AAoA and should be kept active with tiny purchases twice a year. For example, if all your other cards were less than five years, then yes, keep it.