Well, whatever Dhoni does, it becomes a legacy. He is one of the two skippers to have not scored a T20I fifty. Darren Sammy of West Indies is the other one.
MS Dhoni is the also first skipper to score 1000 T20I runs. He has scored 1112 runs as skipper in 72 T20Is with a highest score 48*.
Faf du Plessis of South Africa is the second skipper in T20I history to score 1000 runs. Faf has scored 1003 runs @ 40.12 with one ton and 6 fifties in 31 T20Is as skipper.