That's what beeper.com does. It's also open source, but they handle running it for you.
But absolutely I agree that it doesn't remove WhatsApp from your life, and that's a pain point for me also when I'm working with services in Asia, who like Brasil predominantly work from WhatsApp.
If you don't like Beeper, you could try these guys who host a managed solution (means you don't have to deal with any issues), and let's you offer the service to others: