Seems like it's 1993 all over again. Maybe I'm just over-thinking this.
5YL: Mon-El gets the new continuity rolling by punching out the Time Trapper. NOW: Superboy-Prime gets the new continuity rolling by punching out the Time Trapper.
5YL: The entire continuity is reshaped, in order to remove Superboy’s presence in the Legion. NOW: The entire continuity is reshaped, in order to allow Superman’s presence in the Legion.
5YL: The White Witch, imprisoned on Mordru’s world, is rescued by Laurel Gand. NOW: The White Witch, imprisoned on Mordru’s world, is rescued by Blok.
5YL: Sun Boy appears to be going over the edge, about to become an evil character. (This doesn't happen.) NOW: The White Witch appears to be going over the edge, about to become an evil character. (So far this hasn't happened.)
5YL: The sadistic Dominators have infiltrated and taken over UPGov, and the Legion has been outlawed, until the Legion reveals them for what they truly are. NOW: Sadistic xenophobes have infiltrated and taken over EarthGov, and the Legion has been outlawed, until the Legion reveals them for what they truly are.
5YL: Former Green Lantern Rond Vidar plays a vital role. NOW: Former Green Lantern Sodam Yat plays a vital role.
5YL: Celeste Rockfish is introduced, with "Green Lantern"-type powers. NOW: Rainbow Girl is re-introduced, with "Emotional Spectrum"-type powers.
5YL: Dawnstar is brutally maimed, and loses her powers. NOW: Color Kid is tragically blinded, and loses his powers.
5YL: Blok is pointlessly murdered by Roxxas. NOW: Double-Header is pointlessly murdered by Earth-Man.
5YL: Shrinking Violet loses a leg in the Braal-Imsk war. She replaces it with a blue Probe leg. NOW: Polar Boy loses an arm in the Legion-JLE war. He replaces it with a blue ice arm.
5YL: The White Witch is suffering from mental illness due to traumatic stress, and changes her name to Jewel. NOW: Star Boy is suffering from mental illness due to traumatic stress, and changes his name to Starman.
5YL: Younger duplicates of the several long-time Legionnaires are introduced in Batch SW6, due to a temporal anomaly. NOW: Younger duplicates of several long-time Legionnaires are introduced as the New Wanderers, due to a parallel-universe anomaly. Unlike 5YL, they are never seen again.
5YL: The Earth, in the Sol system, is destroyed in a technological accident resulting from poor judgment in the past. The Legion helps the inhabitants escape. NOW: Titan, in the Sol system, is destroyed in a technological accident resulting from poor judgment in the present. The Legion helps the inhabitants escape.
5YL: The Legion is forced by UPGov to accept sociopathic, psychopathic, murdering Khunds into its ranks. They all die, redeeming themselves. NOW: The Legion is forced by EarthGov to accept sociopathic, psychopathic, murdering Earth-Man into its ranks. He dies, redeeming himself.
5YL: Timber Wolf kills the new super-villain B.I.O.N., despite the fact that B.I.O.N. clearly outpowers him. NOW: Cosmic King kills new super-hero Variable Lad, despite the fact that by any reasonable interpretation, Variable Lad ought to outpower him.
5YL: Tyroc is re-introduced as President of Earth, but somehow it is still unsatisfying. He then disappears without explanation. NOW: Tyroc is re-introduced as a top-tier Legionnaire, but somehow it is still unsatisfying. He then disappears into the past, with the rest of the Legion presuming him dead.
5YL: Timber Wolf travels into the past alone, getting his own book. He becomes more wolf-like. The book is cancelled after a short run. NOW: Timber Wolf travels back into the past with several other Legionnaires, getting their own book. He becomes more wolf-like. The book is cancelled after a medium-length run.
5YL: The Legion is drawn into a battle with between the Time Trapper and Glorith, now re-imagined as a major villain. NOW: The Legion is being drawn into a battle between the Time Trapper and Glorith, now re-imagined as a new Legion recruit.
5YL: Due to the Zero Hour crossover, there is a major shake-up at DC, the Legion’s universe is severed from the general continuity, all the unresolved plotlines go in the crapper, and current continuity is rebooted. NOW: Due to the Flashpoint crossover, there is a major shake-up at DC, the Legion’s universe becomes severed from the general continuity, several unresolved plotlines go in the crapper, and the current continuity is (at least partially) rebooted. (i.e. Secret Origins)