Sorry Grandad - you're barred!

There's a suggestion that, as there's a minimum age for voting, there should also be a maximum age - 65 is being put forward.  I can see the logic - I shall be 80 in a few weeks (Gawd 'elp me!) and statistics suggest that I probably won't see 90 (only a 30% chance).  Those of my grandchildren who are eligible to vote are in their 20s. So should our votes count the same?  In making our individual decisions about how to vote, I only have to worry about the next few years, whereas they need to consider the next few decades.  So should people's votes be "weighted" according to how long they are likely to have to live with the consequences?  I think this discussion has mainly arisen as a result of the referendum result, where it seems (and I still find this hard to understand) that the "leave" vote was mainly driven by older voters, although it is the younger generation who will have to live with the result.