No, but that's only because I hate Excel. But I'm sure developers who don't hate it but also appreciate FOSS solutions might be interested, if the pay is good.

Access = LibreOffice Base

Visio = LibreOffice Impress

Outlook = Schleswig-Holstein already switched successfully to Open-Xchange and Thunderbird, I've not heard of them running into any major issues with this setup.

And if the cost of (re)developing all the existing solutions exceeds the costs of MS licensing for a decade?

I find that highly unlikely given how much commercial agreements with MS costs.

But if that's the case then they should either look for a different COTS solution, and/or change their business workflow.

And in the event even that is unfeasible, then just continue to keep a few windows machines (maybe convert them to VMs or VDIs for ease of maintenance) for the few users that can't be migrated.

Have you, personally, ever had to convert an MS Access based application that took years to write to something else? It seems like all your responses either shift responsibility or hand wave it away. I'm sure migration is incredibly easy when you don't have to deal with said migration in a meaningful way.