King Flevance
Deity
Actually, Civ 7 gives handouts to the leading civ as is. The biggest complaint against continuous playstyle is that it gives even MORE handouts to the leader. Civ 7 actually encourages snowballing, they just use age transitions to "put everyone's snowball on a new starting position" but they either leave everyone's snowball the same size as it already was, or help the largest snowballs get larger.I think punishing people from playing well in the early game by giving handouts to your enemies goes against what a game should do, but well, to each their own
There are many people who would like to see this addressed. I would prefer a system of diminishing returns vs handouts. For example, as is, buying your first settler on epic costs 300 gold. The second, 420. The second is 420 even if you build your first instead of buy. This is not punishing you for making settlers, it is making each one more costly.
In the same way, you can implement ways that legacy points (age currency) can even things out more.
However, this does not address civ switching. I think this would also be a way to let you keep you civ and spend legacy points to do so. In this way, you would forfeit your unique military units and the ability to gain new traditions. However, you would keep your ability to build your UBs and your UA and your unique civilian units.
Although, you could even add a bonus civic tree for new traditions here.