It very surely will not be the only one. The budget committee itself still wants to spend more and I would expect them to submit their own, but probably also not percentage-based.
I wouldn’t have a problem with a percentage of last year’s treasury “income”, only with a percentage of the current treasury balance/stock.
Problems that could arise:
- There seems to be some disagreement how to actually determine it. I was quite verbose in my methodology in https://forum.cardano.org/t/fundamental-critcism-of-the-budget-process/143519#p-367722-net-change-limit-2, but there are quite different figures floating around where I have a hard time understanding what they do. So, methodology would have to be also in the action to be unambiguous.
- What do we do once the “income” goes negative? We can’t spend negative values. And on the way to that, that limit will become smaller and smaller quite fast. Not sure that is really better than deciding on concrete values every couple of years.