This feels like a central question of post-cloud / post-SaaS outsourcing.
In the end, it boils down to two options: offer deep APIs into your product, or don't.
IMHO, what needs to happen to support the former is for every SaaS purchase to include full technical due diligence on external integration capabilities.
Integration needs to start being a headline feature in purchasing. And less an afterthought when a horrified engineer looks at some new enterprise product that's already being adopted.
In the end, it boils down to two options: offer deep APIs into your product, or don't.
IMHO, what needs to happen to support the former is for every SaaS purchase to include full technical due diligence on external integration capabilities.
Integration needs to start being a headline feature in purchasing. And less an afterthought when a horrified engineer looks at some new enterprise product that's already being adopted.