I get the impulse, but term limits for Prime Ministers are stupid. The way to fix Hungary's political system would be to just implement PR instead of the unrepresentative system that skewed elections in favour of the ruling party.
Update:
With 135 supporting, and 50 against, the amendment has been passed today in Hungary's National Assembly.
Prime Ministers are now limited to serve a maximum of 8 years - meaning Viktor Orban can never run again - and Peter Magyar can only serve 8 years too.