With how easy it becomes to write software, I'd say that both the model and the harness are already being commoditized. I don't see a reason to believe there would be moat in any of them.
Software engineering is a sliver of overall economic output. It is an input for tech companies who sell something else (ads, subscriptions, etc.). It is a backoffice expense for non-tech firms that do engineering.
I anticipate that the harness (and memory) will evolve far more outside of engineering. Muse/Dots are an example of that.
