If something like this is implemented, it should send a notification to the mod creator and give them at least 48 hours to respond before putting up a big banner saying "this mod is outdated". Frankly, a lot of users are idiots, and will say "your mod is outdated and needs to be fixed!" when in fact the user has merely installed it incorrectly or has other issues with their game. If the file is updated after the notice is posted, then the notice should be removed, as that would indicate the mod has been updated.