People don’t stay in power just because they haven’t died yet. Not even dictators, there is much more in staying power than just passing some law or a vote that you are the leader for life now. You have a overly simple view of power.

Beside , constant changing of leaders or terms limits are not even necessarily a good thing, even in democracy. While one can argue that it prevents entrenchment of leaders, but one can also say that constant exchange of cabinets and leaders leads only to short termist thinking and weak, ineffectual leaders and governments who are more concerned with the opinions of media and their funders because of fear of being ousted in the next election otherwise. While a longer standing leader can take more long term projects and act with more confidence and long termism is excactly what we need right now in every government, but the system is set up such a way to prevent that, because that is basically the core pillar of liberalism short termism and weak leaders, that let things and the actually powerful people be, that is. Term limits are basically to prevent that a actually popular leader, with a good track record can not stay in power even if they still could win elections and they have to be replaced with a weak noobie or a favourite of a the oligarchy.

…just a thought.