Put it about 20 or 30 years after Turn-a or maybe alot more, just keep that cry baby Lauren away from any mobile suits (He by far had the lowest actual Kill count of any Gundam Pilot) Shameful i say.
You're just bitter he wasn't a newtype.
I thought he was great and his combat skills was likely better than a lot of stuff from many other series because he wasn't facing hordes of paper-tigers.
There was some semblance that at any moment, anything could go awfully wrong and for that, it felt strangely authentic.
Maybe it's set some 100 years down the line.
If you actually want a plot-arc, maybe there's some revival of the Black History or some nut discovered Zeon's legacy, spent some years in space to ponder things and we're left with what is essentially a Zeonic Che Guevara
convinced of his ideals who may have originally meant well but now is the greatest risk to the Earth Sphere.
With a backing of people behind him willing to support him and access to mobile-weapons noone on earth does, the world falls into ruin and a system of control as technology surges.
Maybe here, we could go into the way Turn-A seems to unify Gundam: Going as far as there even being alternate realities in which things have happened differently - and maybe even going as far as to throw ideas into the wind about why Gundam continues to arise: Maybe it's something 'set' into reality that triggers to resolve a particular scenario humans suffer, set by some great unknown force, felt by the NewType and the PsychoFrame.
But that egg, left by Turn-A and Turn-X. I mean, Turn-A was a gigantic nano-mechanism: Who's to say Gundam won't return to resolve the situation?
I could throw my theory that the twins are Char's descendants but then things get strange.
What do you think would work?