Tangential note - The data-lockin is exactly why I don't use Slack or that litany of SaaS solutions out there. Even with Oracle or MS SQL Server (or even Azure on-premises), if I needed to I could bulk copy my data out.
Open source + charging the enterprise a lot for customized solutions and/or paid support is a fantastic model and I wholeheartedly stand with your model.
(N.b., marketing strategy -- capitalize off the fact that everyone's data is being tapped now - e.g. Dianne Feinstein, in charge of the Senate Intelligence Committee's, had her staffers machines hacked - Apple is 100% hackable too (see: the San Bernadino FBI debacle) and offer secure comms at Blackberry Enterprise licensing pricing. I'd estimate > 95% of F500 is MS based/LDAP based on my experience. They're used to paying tons of money for Remote Desktop/AppX/Citrix/Exchange/whatever seats. You could easily get away with $60/user/seat + install fees + 50% for platinum support.)
Open source + charging the enterprise a lot for customized solutions and/or paid support is a fantastic model and I wholeheartedly stand with your model.
(N.b., marketing strategy -- capitalize off the fact that everyone's data is being tapped now - e.g. Dianne Feinstein, in charge of the Senate Intelligence Committee's, had her staffers machines hacked - Apple is 100% hackable too (see: the San Bernadino FBI debacle) and offer secure comms at Blackberry Enterprise licensing pricing. I'd estimate > 95% of F500 is MS based/LDAP based on my experience. They're used to paying tons of money for Remote Desktop/AppX/Citrix/Exchange/whatever seats. You could easily get away with $60/user/seat + install fees + 50% for platinum support.)