If content and devs are focused on player retention and gaining new gamers as a result of sheer quality, that's a bloody good thing. I think Jagex already knew that OSRS gold would be the primary driver of profits without the cashcow mechanics, but are experimenting with the RS3 playerbase.
The reason I say all this is idt that Jagex are gunna start pouring their resources to OSRS and shooting out updates every week. It isn't broken in the minute, and it is a delicate thing. The'potential of Jagex' isn't attempting to speed up the process we're seeing for the two games, it's about keeping the momentum moving without breaking it. It's clearly working as is in the moment.
I'd indeed very happily play OSRS' gameloop in a similar styled contemporary universe. I am unsure how many others would but I certainly would love that shit. I remember I'd like to google all the time back as a kid hoping for mechscape leaks/updates (Although I seem to recall the project having another alias as well but I can not remember it today, I think it started with an s or an a).
Like RS3 even is getting into dealing with multiple planes/planets/worlds, doing the same using a mechscape would not be too out of the Buy Rs gold question. And skills can be altered in name. Hell, we could even go more outlaw star or star wars inspired and have magic.
I'm not against Jagex making a brand new game, they have got good employees on board who could surely make something happen in a different genre. Could being surgical, needless to say