Why would there need to be a hard limit on something the electorate is already directly voting on? You might say every election is an election on if people above X age should be in congress.
Not sure what is the solution, but if people say they would prefer younger "options" and they don't materialize on the ballots, that is a sign that the system does not work as intended.
Which really makes you wonder how well the system is really working. Of course I don’t know this but I feel like if you asked everyone, the majority of people would say that 95, or 90, or 85 is too old to be in congress. But somehow they keep getting reelected…
Aging population means that many democracies will have more old than young voters. Couple that with the American culture of f you I’ve got mine, leads to a prioritization not on the future generations.