It is the right question, and it should be asked out loud. A system no one can support is a liability, not an asset. The fear is rational. Most vendors dodge it with a handshake and a promise that they are not going anywhere.
That answer is not good enough, because it depends on the one thing you cannot verify: that a single person stays reachable forever. So Heed does not sell single point of failure dependencies. Support is contractual. Documentation is complete. Ownership has a defined path. The model that built your system is never the only thing keeping it alive.