The problem with changing from company-owned servers to private servers is the question who will maintain the server software.

Making it open source is not always an option because I can imagine there is a lot of shared code with other projects which the company want to keep propriety. This means the company would have to maintain the code for others to be able to host the servers, which I doubt makes financial sense.

I guess that makes sense. Thanks for the insight!

Preface: I am no game developer, but I am a software developer

This comment does not make sense to me. There is no “simply” bringing any game to any other engine. Doing this is a huge undertaking and I can’t imagine not basically starting from scratch, saving the art assets and bits of pieces of the code (given it’s written in the same language).