On the other hand, what are the odds we're still using them in 100 years? Almost none.
The next question then must be: when do we start writing the next generation of tools? Now, or should we wait?
>>On the other hand, what are the odds we're still using them in 100 years?
Firstly you are not going to live for the coming 100 years. So lets not worry about impossible scenarios.
Secondly next generation tools for the next hundred years need to be designed such.
The original code for vi was written by Bill Joy in 1976. So, if we applied Gott's Principle and estimated the maximum upside of how long we'll be using Vi or Vi-like editors:
36 years × 39 = 1482 more years of Vi.
If I want to use vim, I can use vim. Heck there are many things these days that will give you the same GUI candy what GUI based text editors give.
Glossy text editors come and go every 2-3 years, Editors like Emacs and vim stay.