A combination of customer support chat (Intercom), customer relationship management / sales (Streak, NetHunt), and customer payments tracking.

So basically, the stack that is needed to handle B2B customers as a startup.

Currently these tools are very isolated, and where integrations exist, they are poor. We have to manage customers in 3 different systems that don't know about each other. When making sales progress on Intercom, it doesn't reflect as conversations in NetHunt.

Open-source would be excellent because Intercom is currently problematic with GDPR and high-security systems that don't like to embed third-party Javascript. The ability to self-host solves that. Most people will still use the hosted service you can offer if reasonably priced.

I hope that https://www.chatwoot.com will do this, but they are currently focused on only the Intercom part.

The services also don't necessarily have to be fully vertically integrated in 1 product as long as they interact well. For example, and add-on to Chatwoot that does the equivalent of Streak/Nethunt, something with good API integration, might also do the trick.