Sailboats are luxury items, dude. People aren't forced to use sailboats. In fact, instead of 100% of ships being sailboats, I'd gander only 5% or less are sailboats.
5% of the sailboat market is pretty significant - as is 5% of the computer market. In fact, iirc, Apple has been making solid profits from round about 5% of the laptop market.
Anyway, I was merely illustrating that "the future of" does not mean "the sole replacement of".
