Make a private (non-OSS) version optimized for Business (B2B), do external consultant jobs and pretty much ask for donations from the big players/users. This is a common problem from almost every OSS project and so far the only one that is doing this is OpenSSL.
1) An Stable "enterprise grade" version which receives fixes and minor performance updates for at least 5 years, maybe even charge extra for another 2-5 years round (just like Microsoft does).
2) Reports: Business love reports, if they add a way to generate reports straight from the DB (like Oracle and SQL Server) is a killer feature most of the time.
3) Customer Support.