Your so-called Jagex's "major competitors" don't seem to be doing anything to OSRS, at least nothing visible to OSRS's "playerbase" - yes, it has been dropping fast the last few months, but now that "major competitors" have released their old school version today but it doesn't seem to be making it drop any faster.
You know what? The "major competitors" only released 14 servers for their "old school version" altogether. Yes, their fanboys are going to say "WoW! A lot of waiting in queues" but of course that's because of their small capacity.