This year, the migration projects I have worked on were some of the most fun. Migrations have changed from the death-by-1000-cuts that they were, to the which-AI-method-to-best-ensure-100%-fidelity. So, I don't believe the "very hard" part. Obviously it would involved recreating or reshaping many features that very involved in an integration to have a disruption-free move, but I think the complexity is manageable for most companies if they put in some effort.

This fun was not revenue-generating, I suspect, so it's already a loss. Also it's a long-tail change, which will likely create unexpected situations here and there, and de-value experience and knowledge already available. Cumulatively it can be much more expensive than staying, unless GH will continue to falter, of course.