FG = The New Skateboarding (this time it's true)

but given theres different ways that people use fixed gear bikes surely only "fixed gear freestyle" is like bmx, just using track bikes on streets isnt really a discipline.

Right, using a track bike (fixed gear bike) for tricks (FGF from now on.) could be considered a 'discipline', be it a discipline of BMX (wrong) or a discipline of fixed gear riding (right, and called FGR, from now on.) in general.

what about longboards? its like skateboarding, but you just go real fast down hills instead of doing tricks, street skating is only one disipline, like vert and bowl skating.

Right:
BMX=
flatland
ramp
dirt
jump

skateboarding=
street
vert
bowl
downhill/longboarding
slalom
the now defunct freestyle

FGR=
cycling
track
FGF
anything else?

rollerblading=
street
vert
sitting on your arse on the ledge annoying the street skateboarders
slalom
track (speed skating)?

along this thread, people who ride nobrakes say its makes them more fluid and shit, couldnt you compare that to how skateboarding started, imitating surfers and how smooth they were on the waves, then it changed to street stuff, a bit like how people took off their track drops in place of risers and hey presto you get rollerskating.

nobrakes making them 'fluid' is bullshit*. But I can see the logic you're coming with.

My big thing is FGF has not proven it's worth and longevity. Like riding rollerblades for tricks has not and will not.

*and I sometimes ride without a handbrake, and did for about 4 years straight.