Before OSRS came out, 2006 servers were doing fine. I remember the playerbase on here drop so dramatically in a week because of it's release, it was insane.
Funnily enough since you made me think about it, I'm the only one who plays RuneScape left out of everyone who used to play back in school with me, on our shitty Internet Service Provider being screamed at by our parent's to come downstairs for dinner.
The thing is, people might play 2006 for a bit out of nostalgia, but that remembrance of their past soon becomes less strong because they have the ability to play the game again.
Sometimes you don't realise how much you loved something until it's gone. If, like RuneScape, it comes back, you stop missing it again.
I'm tired so sorry if I didn't word this correctly.