What has changed most dramatically is the "fixed" cost of writing the software to begin with. Given that the costs were being spread out over so many units beforehand, it's not entirely clear to me how that changes a lot of the economics.
For the comments about the "SaaS vs build your own", we can use a home services metaphor. Sure, I can do a lot of what my plumber does. But they do it faster, know all of the issues that go wrong with the work and I can pay them a yearly fee to check my boiler to make sure it doesn't fail etc. The time saved by calling the plumber can then be spent with kids, more work or a combo of the two.
Their lead has shrunk, and thus so has their value.