What happened to the mane 6

[Fluttershy214 4]

Anybody wonder what happened to the mane 6

[Venomous 18,813]

They passed away.

Given how much time passed between the ending of G4 and G5, it’s more than safe to say that they’re dead.

[Courageous Thunder Dash 7,809]

Because of the timespan between G4 and G5, they all passed away, with Twilight outliving her friends (as some speculate). Their memories live on however. 

[Splashee 28,537]

The show, however can never use the word "dead" (like with Applejack's parents). They have probably moved on to some wonderful place somewhere. But G5 is taking place so many moons later than G4, they are most likely gone forever (unless they get so popular they will be brought back like the Pillars were)

[Evil Pink One 12,928]

maybe they got lost on limbo....nahhh.... they dead

[Sonic Shimmer 4,116]

They're all dead.

Spoiler

Dead serious about going to Itchy and Scratchy Land.

 

[Goat-kun 2,490]

They're dead, Jim....

[Brony Number 42 9,886]

Seems like we are all thinking the same thing.

[Ganondorf8 11,118]

They are no longer of this world though Hasbro won't say it in such an obvious manner because it might set a bad precedent. It's possible some other characters from G4 are still alive in G5 provided they either have longevity or are immortal, but we haven't seen them given that the G5 movie did focus on the three pony tribes first and foremost.