I think item #2 in your list is the real kicker here. Given that AI can write code the threshold for "trivially replicable" is going down.

Unless your thing has strong network effects or a large capex requirement (ex: GPU infra) its easily replicated and I think that's really what makes things hard.

Most business software that was truly trivially replicable with AI, was already trivially replicable with the prototyping tools we had available.