Former Indian captain Dhoni turned 41 on Thursday.
However, Sehwag maintained that if the team management sticks with its current policy of having one captain to lead India across the three formats, then Sharma is still an ideal choice.
Sehwag's inclusion in the Test team for the 2007-08 Australia tour for the Border-Gavaskar Trophy surprised many.
Sehwag added that New Zealand pace bowler Shane Bond, who is currently the Mumbai Indians bowling coach, was the toughest fast bowler he faced.
The West Indian mystery spinner will play his 150th game for KKR later on Monday.
Tewatia struck consecutive sixes off Odean Smith in the final over to snatch victory from the jaws of defeat.
Saha's tweet came after he was excluded from the squad for the two-match Test series against Sri Lanka.
The left-arm spinner, who took all 10 wickets in the first innings of the Moumbai Test, posted on Twitter that Sehwag had hit him out of the park during his stint as a net bowler in the past.
The 71-year-old coach produced cricketers like Surinder Khanna, Raman Lamba, Manoj Prabhakar, Ajay Sharma, K P Bhaskar, Atul Wassan, Ashish Nehra, Sanjeev Sharma, Aakash Chopra, Shikhar Dhawan, Anjum Chopra and Rishabh Pant.
Former cricketers lined up to slate Virat Kohli's Indian team after Sunday's crushing eight-wicket defeat by New Zealand left them on the brink of elimination from the Twenty20 World Cup.