I think the best option if time-scaling was implemented, is for it to only be available in Solo mode. Time-scaling in Live would be disastrous, and not a great option, and when flying online using Vatsim with FSX, if you use the time-scaling (sim rate) feature, you are banned from the server. It’s not a good idea for active airspaces in a multiplayer scenario.
Either time-scaling is only available in Solo, or available in Solo and Casual. I’m honestly not too bothered about not having a time-scale option though. Most people who complain about it are probably happy to spend 5+ hours on their Xbox or Playstation, so I don’t think anyone will be too affected by it.