That doesn't guarantee it will have paid contributors indefinitely, but the same is true of the other editors you listed. It does, however, guarantee that if Zed (the company) were to disappear, community members would be free to continue using the Zed editor (and developing it) in perpetuity!
The problem is the concern of future development. Zed the company controls what gets merged. If it is profitable to leave some features out, will they leave them even if there is PR? Or something else. Compare it to the problems of Chromium.
That doesn't guarantee it will have paid contributors indefinitely, but the same is true of the other editors you listed. It does, however, guarantee that if Zed (the company) were to disappear, community members would be free to continue using the Zed editor (and developing it) in perpetuity!