On Jadeja - you can't drop an entire team. I full agree that his career is winding down, but the Indian team has more important issues - who are the long term bats not named Jaiswal? Who can support Bumrah beyond Siraj? Does another elite AR exist? - to solve before then.
(I can't answer the last two, but while India can't throw out the baby with the bath water, Sai Sudharsan and Sarfaraz Khan deserve more of a shot, and maybe Ruturaj Gaikwad/Devdutt Padikkal if they fail or other spaces (looking at that of Gill) become available