May seem like an obvious one considering where we are but standards for communication apps
If everything uses a standard like activitypub/matrix and becomes cross compatible I don’t need to have 6 different messaging apps
Provided the standard is completely backwards compatible of course I think it would be awesome to just let people have their messaging app of choice and be able to talk to everyone else (I think there might actually be an EU regulation coming that enforces this for larger messaging apps)