AI is simply another form of what we've been doing since the dawn of computers: expressing real world problems in the form of computations.
While there are certainly some huge jumps in compute power, theory of data transformation and availability of data to transform, it would surprise me if computers in a 100 years do not still rely on a combination of well-defined and well-understood algorithms and AI-inspired tools that do the same thing but on a much bigger scale.
If not for any other reason, then because there are so many things where you can easily produce a great, always correct result simply by doing very precise, obvious and simple computation.
We've had computers and digital devices for a long while now, yet we still rely heavily on mechanical contraptions. Sure, we improve them with computers (eg. think brushless motors), but I don't think anyone would be surprised today about how did anyone design these same devices (hair dryers, lawn mowers, internal combustion engines...) before computers?
