> AI?

Probably not; this point is well justified by both theory and practice. Supporting suitably larger operands is indeed what naturally comes following the increase of computation demands.

One point I do differ from the author is that register width don't necessarily correlate with the size of address space. Even 8bit machines can address a large space by splitting apart the logical address and using multiple registers. Likewise, having a wide register does not imply the same address width.