Many are still around to some degree. OS/400 is now IBM i. MVS is now z/OS (for IBM mainframes). OpenVMS as you say. Most of the operating systems that were originally written for minicomputers aren't radically different in fundamental design from Unix and Windows NT.
My suspicion is that, absent Unix or something that followed a similar historical trajectory, these OSs would have had a longer run as non-legacy products, the landscape would have been even more fractured than it was with the Unix wars, and Windows would have become more dominant in the server space than it eventually became.
The question I really don't know the answer to is whether, given the rise of the mainstream Internet, an open source operating system and infrastructure software necessarily would have followed. Or would the world look very very different.
My suspicion is that, absent Unix or something that followed a similar historical trajectory, these OSs would have had a longer run as non-legacy products, the landscape would have been even more fractured than it was with the Unix wars, and Windows would have become more dominant in the server space than it eventually became.
The question I really don't know the answer to is whether, given the rise of the mainstream Internet, an open source operating system and infrastructure software necessarily would have followed. Or would the world look very very different.