he should be sacked and Karthik to be brought in. India can form 3 different team for each format. so much talent is available and more players can represent india. Competition will also be healthy for players. these deeee gaaangg chammmcha dhobi blocked so many talented south players with his chamchaas. Namo now effectively sealed the betting by demo.
With the experience & the exposure Dhoni has,he should bat at the number when the team requires runs to win ie his batting no should be flexible in the team.He should be used as the Ace Player of the team.
He should bat at no 3 or 4. He should be given enough time to play more and score more for India. he has tremendous batting capacity, that should not be wasted making him play at no. 6
There is nothing like at what number a certain batsman should bat,it all depends on the particular game,pressure, adaptability etc what matters the most is consistency.