I think 260-280 would be a winning score in ODIs with new rules....
Once bowlers adapt to 5 fielders outside in final 10 overs, they can bowl to the body with 4 players on the leg-side fence.
60-80 runs in those 10 overs might be expected.
You are correct. 271 was always going to be difficult.
First one day was an exception where around 100 runs were scored in last 5 overs. That was because our bowlers didn't know which length to bowl and also the ABD factor. Other than that, it is already proven that getting 300, batting first is not easy unless a team bats exceptionally good. And chasing, we have already seen two matches in a row how difficult it is.
Sanju Samson would suit better at number 6/7. Right now that seems to be Dhoni's target, to find his replacement at that position. Rahane is a top order guy, and he can't play at 6/7.