What I am going to say I would have done earlier in SRT"s career.
I would take time off from International cricket after talking to the selectors. Go and play in first class cricket in another country. England, Austraia or South Africa will do. He will be taken with open arms by most sides. Their gates will soar. Crowds will fil the grounds to see him He will be relaxed and should play to enjoy himself away from the scrutiny of the Indian media and public. I would ideally play the rest of this winter in Austraia or South Africa and the summer in England. At the end of that period, rejuvenated and, hopefully, with runs, form and confidence come back, choose any one series from the next season, announce it as his last series and play with gay abandon. If he feels unto it, chose two series, one at home and one away but be very clear before joining the team. aAnnounce that this is your swan song.
He will be loved, all that has happened in the last two years will be behind him. He should be clear that he is not going into those series to set the grounds on fire. He is going to them to be in a better frame of mind then today before he starts his announced last season so that he is relaxed and the brickbats are behind him.
If his health permits him another year, I think this is what he should do.