Did Ambedkar want reservations to last forever?
Not the political part of it, and here his own design has to be read carefully. Reservation is not one thing but several, and only one of them was given an expiry date. The reserved seats in the legislatures were written to last ten years — the clause Parliament has since extended every decade — which shows they were conceived as a temporary safeguard for a young republic, not as a permanent fixture. He expected the need for reserved seats to fall away as equality became real.
He was, in fact, the sharpest critic of political reservation on one point: a seat reserved inside a joint electorate is filled by the whole electorate's votes, so the winner is the candidate the majority finds acceptable rather than the one the reserved community would have chosen. He made that objection from before the Poona Pact until he died, which is not the posture of a man who wanted such seats to be eternal.
The other parts — reservation in public employment and in education — carry no ten-year clause and never did, because the disability they answer is exclusion by birth, which does not lift on a fixed timetable. Whether any of this should continue, and for how long, is argued fiercely in India today; but most of that argument concerns policy made after his death in 1956, and this site keeps to his lifetime and does not follow the argument past it.