As bleed duke blue has stated, it isn't as popular (or populated for that matter) as it once was. There are quite a few popular streams on RS (mainly osrs) on twitch. I still don't find it nearly as close to what it once was though.
Hmm.. on the making a comeback, it is really hard to say, but I honestly don't see it getting back to where it was.
It's no way near as popular as it once was, and I can't see it coming back honestly. It depends, this legacy update might change things.
I think they're doing fine and I think the game is still enjoyable for people who aren't so hell bent on being anti-Jagex. I've been playing on and off since 2005, I've gone through all the changes and I've never had a significant problem with what they've added. They don't have the concentration of sheer die-hard players that they used to, but I can't help but wonder if that's because the mass of those players have naturally moved on, not just because of the updates, and the new generation haven't quite discovered RS (since they don't advertise that well compared to say WoW) or are more interested in other types of gaming besides MMO's.
I can see RS going strong another 5 years at least.
Runescape has effectively diminished interest in a portion of it's players' eyes, without a doubt. Honestly speaking, I boldly would state that botting was quite helpful to the game's allure. Obviously, within reason, I could recall not being to fond of passing by 12 tutorial island studs huddled around a yew tree. But alas, that was a niche, Andrew Gower's uniqueness; his touch, if you would has disappeared.

