I agree that 100 years is too long. Hashrate is increasing. Number of transactions is increasing. Adoption is increasing. As the article goes on to say, Jack Dorsey (CEO of Twitter) thinks there will be a single global currency within 10 years, and it will be bitcoin. I think 10 years is too soon for bitcoin to be a "single global currency", but we will certainly know in 10 years whether it is heading that way, as Satoshi predicted. I suspect it will be.
No doubt he wants to be first in line to consolidate authority over the bitcoin network, so he can then retrofit Twitter's draconian censorship policies on top of it.