My guess is that they'll open source more stuff. Nostalgia is a powerful tool, and Microsoft's reputation is worse than that of FAANG, in many circles. They know they need to work on that, my guess is that it's primarily a priority/budget thing.

Someone needs to work on these releases and the big ones can be scary, especially from a legal point of view. So they'll just slowly release one small item at a time, and hopefully over time most of them are out in the open. Maybe we even get some big fish, like Win98.