People have been able to support creators directly for a very long time. That's a rare occurrence. Without a sizeable consumer base roaming around, people are unlikely to find that support. Even if curation placed it front and center.
I'll return to rigid guidelines. Not many think outside of that box. If the content creator wants long term support, all they have to do is ask. Set up a subscription model for yourself. If people see value in that, they'll pay for it. It's not up to the system to do these things for people. The tools and options exist. Pick them up and use them.
People also have the ability to leave a comment under an old post, then upvote the author's response. Wouldn't be wise to upvote 5 year old content. Don't even know if that author is there anymore, until they respond.
I'm not sure what makes people think every upvote needs to contribute to curation. The upvote is curation, the rewards are support. That button performs two things, not one. It's flexible. But again, it's up to the people to think outside of the box.
Any system offering long term rewards first needs money coming in the door to pay for those rewards. I've been stressing the importance of building a sizeable consumer base locally for nearly a decade.
People forgot how to busk and build an audience. It doesn't require advanced technical solutions to solve a simple problem.
These are some good ideas for people who may write valuable content that is useful overtime. I mentioned it because I know this was an issue raised from time to time, but I agree it would be unsustainable to pay content longterm from inflation.