Why can't the Unicode consortium not reserve codepoints for the next 10-50 eras and simply wait with filling in how it should look and what to be called?
As jerf pointed out [0], you can do that but once you print that unknown symbol, the Unicode consortium can't really do much.
Also, you can't just say "well, next era begins on September 1st 2054, so let's write that in our date calculator" - precisely because you don't know when an era begins or ends before it's close.
