Dhoni is still a very capable player. We all already saw how well he has played in this IPL season. His hands are still the fastest for any wicketkeeper in the world in my opinion. He can obviously play one more if he wishes. Actually, I will say that as long as he can contribute to the team well and is not a burden on the team he can play. So, I don't think it is a problem if he decides to play one more season in the IPL. As long as he performs it is going to be entertaining.
CSK winning IPL 2023 under Mahi captaincy says all about his performance. Mahi is almost 42 years old and his fitness clearly says that he is fit for coming IPL. In last IPL, CSK tried Jadega as captain and that test failed miserably, as CSK won only 4 matches and finished 9th on points table. But CSK must try to look for replacement of Mahi in coming years. Its better to find and groom new captain under Dhoni leadership for long term benefits of CSK.