It's very hard to say because most of us will not be around anymore in 100 years but I'm sure that the internet will still be around but will change drastically over that time.
Even looking 20 years down the road from now the internet will probably be vastly different than it is today.
A lot can change in 20 years and a heck of a lot can change even more in 50- 100 years.
20 years ago was 1997 and the internet was slow and vastly different. People were using slow computers, slow internet and youtube, wasn't around. We didn't have tablets, I phones, etc.
It'll be interesting to see where the internet and the world is at in 20 years.