No surprise there. The best Runescape days were 2006. 2007 was just when tons of people were playing.
Runescape isn't dead (yet), it was just massive back in the day. Everyone had shit computers and runescape could be ran on a hamster wheel. Plus online gaming was still pretty new and runescape was easy to play, free or cheap membership, and was a very advanced MMORPG for the time. Back then, you either played WoW if you had the money/computer specs or RS if you didn't have that.
Personally, if they didn't remove free trade, I bet runescape would've still evolved into EoC, it just would have more players. I can't see runescape growing until Jagex fully acknowledges OSRS and treats it like it should be. Look at it, its pathetic. ~8 developers for half your player base? And for months letting it constantly getting DDoSed? Letting OP stuff like zulrah/nmz/splashing/wyverns stay in the game? They're driving it to the ground. RS3 isn't going to grow, but I don't think it will die anytime soon either.