I 100% agree with you. I want this product to make money so that I can devote my full time to it.
The basic functionality will always be free without ads and tracking. But there will also be a very affordable ($1-2/mo) premium plan. I haven't yet decided what it's going to have. Most likely an ability to add more than 5 accounts or multiple accounts on the same platform (e.g. 3 Slack profiles).
Examples:
- Conversations, the Android XMPP client, is GPL and sold on Google Play: https://play.google.com/store/apps/details?id=eu.siacs.conve... - There is also a paid hosted XMPP service on conversations.im.
- I have a paid+OSS app for amateur radio geolocation on Google Play myself. You can download the APK from the homepage or just directly buy it for some bucks.
- X-Chat, the OSS IRC client has a paid Windows version: http://xchat.org/windows/
You could OSS your app under whatever license you want, and still provide paid builds for any platform you want.
I don't want to charge a lot for a chat client, but these prices are not final. I know that charging too little is a mistake.