Companies in most cases don’t want to build SaaS because it is expensive to hire engineers to do it, not because they are allergic to owning teams.
If in-housing becomes substantially cheaper than the alternatives then companies will adapt.
But even if the new equilibrium is to hire a contract dev shop to build something custom to keep avoiding responsibility, this would have the same impact on SaaS.
So I’m pretty skeptical of this first-principles prediction expressing right level of uncertainty.
If you can spend $10K/year to keep your in house one alive but $5K/year on the new SaaS option, you stop building your own again.
Whose job had been maintaining a single internal system but had never had the bandwidth to expand their focus.
Companies like that are the ones spending millions a year for large one size fits all SaaS products.