Essay time, Yay!
There's different reasons for them all to go next.
Gaga has boxed herself into a corner with her message and music, and whatever she does something's gonna give; if she abandons her 'WE WERE BORN THIS WAY BABEH!!!!1!" stance will her stanbase remain? But if she keeps that message will the public stay with her? She could end up fading away and then there would be nothing to stan for.
They also seem to turn on each other with great ease so that could rip them apart.
"Britbots" ~ If they are still fans now, they're not going anywhere anytime soon. Though I could easily see her not releasing anything else for a long time, thus her fan base will start to die off as they move on. Same with the BeyHive - They're not going anywhere anytime soon, unless Beyonce disappears for half a decade to raise her child.
Navy.
If Rihanna self destructs like people predict practically every time she tweets her fan base will probably follow, otherwise they'll be fine. There's no point worrying about her disappearing for 5 years anyway.
Katy Perry Fans (I refuse to type the other thing.) and "Barbz" are quite new as major fan bases and are so probably the most volatile. A massive chunk of Katys fan base, from my experience, seem to be mainly about the hits, and as soon as she stops producing them I could easily see a load of them dropping off. Not seen much of the "Barbz" so I'm not gonna comment much on them, it'll all depend on if Nicki gets bigger or flops on her ass with the next album.
Therefore I'ma vote Barbz. I can't vote for my own fan base!
Edit:
Obviously all my own opinion, there's no point in ripping this apart because you're not gonna change my mind on most of these points. Twas just a word vomit of whats going through my head on this topic.
sorry if it was specifically directed at them 
