Good idea to mention the scientific notation. As it really is different from the positional notation. You can express some numbers in a shorter way then in the positional notation. Thats pretty nice. A variable length encoding with compression.

As for different bases: I consider these very similar to base 10. Maybe we will use base X in a million years, but that wouldnt be a big surprise. I was more thinking about a revolution like from "............." to "13".