Heroku PaaS itself is proprietary. Their dashboard, monitoring and other tools are proprietary.

PaaS services based on open source PaaS solutions (Deis + Docker, Flynn + Docker) and proprietary PaaS solutions ( Tutum + Docker, for example) will look after my infrastructure. Or I will host it myself. In any case I'll be able to migrate my containers to any other infrastructure easily, quickly and with nearly zero additional configuration.