I think cryogenically frozen people will be the mummies for the futur.
Imagine you're in the year 4000 and you goto a museum.
"Here in the 2000s museum we have the head of Walt Disney, he was a famous warlord who destroyed his enemies and demanded caricatures of animals like the extinct Mouse and Dog to be drawn. He had many castles built around the old world in places like Florida, France and China"
I just read that book recently, before covid. I originally read it when I was young, and found a copy to reread through inter-branch library loan. It's a really fun read.
They are preserved in liquid nitrogen. There is no need for electricity, although the liquid nitrogen must be refilled once in a while (something like once a month I think). Liquid nitrogen is pretty simple and cheap to produce. Now of course if society collapses before we are able to bring those people back to life, then they will indeed rot.
It's a matter of record that Walt wasn't cryogenically frozen and was actually cremated (and there's exhibits about that specific point in the Walt Disney Family Museum). It'll be as easy to disprove in 4000 years as it is now, especially given that records are much better these days and we have tens of thousands of copies of everything.
Saying "People will forget stuff and make up things about the past" certainly works for ancient history but I don't think it'll work so well in the future. We can store and retrieve the sum of human knowledge (at least the facts, but other things too). There's no reason why we'll ever stop doing that. Accuracy and context for basic information like the manner of someone famous's funeral won't be lost.
Imagine you're in the year 4000 and you goto a museum.
"Here in the 2000s museum we have the head of Walt Disney, he was a famous warlord who destroyed his enemies and demanded caricatures of animals like the extinct Mouse and Dog to be drawn. He had many castles built around the old world in places like Florida, France and China"