It’s not necessarily straightforward or cheap to migrate a living product to open-source land. Backend services at Google are built using proprietary frameworks

It’s not necessarily straightforward or cheap to migrate a living product to open-source land. Backend services at Google are built using proprietary frameworks and infrastructure for which no equivalent exists out in the real world. They could help people out a bit by open-sourcing the web front-end, but that’s substantial work and you’re still a long way from having a working clone of the product. EDIT: I see I misread your comment and you’re talking about keeping it on Google infra but separating it for accounting purposes. It’s an interesting idea but I don’t see why it would fundamentally change the viability of the product. Also, there’s an ongoing maintenance cost to having more products on shared infra. If you’re the team that runs the global distributed relational db (for example), or maintains the C++ discrete optimization library, it’s much simpler to support two products that make a billion each rather than 2,000 subtly different use-cases each making a million each. Not to mention costs incurred by non-engineering departments (marketing, accounting, legal).