Nylas is open source, like Ruby on Rails, so you can run it yourself.
Nylas supports many providers, including Gmail, Yahoo, and Hotmail/Outlook.com, with plans to quickly add more. The Nylas Developer Program also supports Microsoft Exchange for enterprise users. You can build once for users everywhere.
If you find a bug in Nylas, you can submit a pull request and help fix it. If you have an idea for a feature, you can fork Nylas to add it.
Nylas is an email company. Google is an advertising company. This product is our focus, and will not be "discontinued" unexpectedly.