Hard disagree, “SaaS” will not die, but it will evolve.
Will there be some companies that will build all the tooling and systems they need from scratch via AI? Sure. Just like there are people that like to grow their own vegetable garden. The vast majority though will continue to rely on grocery stores for the majority of their sustenance, either because of convenience, or because they prefer ready to consume goods, or inertia, or really any reason.
Does that mean that SaaS business that remain static will stick around long term? Probably not. Just like grocery stores have evolved with the advent of InstaCart and Amazon/WholeFoods, so will SaaS.
I do expect some further SaaS consolidation, to bolster platform breadth as well as to drive overall cost of service down, “your margin, my opportunity” style capitalism.