You know, it's not a simple question, but there's some case for Microsoft just up and releasing some scale-out DB for free (as in beer) or at least cheap.
My thinking is, scale-out deployments aren't all that likely to pay at SQL-Server-like rates per CPU anyway, and you're helping give the Windows world better parity with the horde of Linux options for folks that need scale-out (or, just as commonly, hope to need it someday).
On the flipside, by doing that you might forego some sales of SQL Server (though I suspect that's limited; most folks that need SQL Server really need SQL Server) or sales on Azure that could theoretically help recover the dev costs. But greatly improving the scale-out-on-Windows story seems like a big deal, the kind of thing that might justify going to lots of effort to make a DB product then giving it away.
