If even 1/4 of these are members (there's likely more) that's nearly 200k/month from membership on OSRS alone, not to mention the amount of people that purchase bonds, etc.. Their shit servers probably cost them little to nothing, and they probably pay their staff even less (the most likely reason they're leaving).
Nowhere near the end, this is a cash cow that will continue to exploit as much money as possible.
Look at D2, game has been dead for a decade yet blizzard continues to host somewhat reasonable servers for it. Could they shut down bots/shops? Absolutely.. but you don't think they're seeing a profit from it in another way? Disable keys, make you purchase more, rinse/repeat.