You're wrong about Superboy in the Legion. Hypertime is not involved.
Both Clark Kent (from Man of Steel continuity, not Birthright) and Kon-El (Superboy) are involved in the story.
The Superboy dressed in the classic look is Kon-El while Clark Kent has been turned evil by Darkseid. He's the one the Legion and Superboy are fighting on one of the covers of the series.
If you want looooooooooooooong term change on a MAJOR character then look for further than Wonder Woman.
I dare you to claim that she's the same today in the Rucka comics as she was in the Perez comics.
Back then she was an innocent 17 year old, wide eyed teenage girl and now she's an experienced warrior, a grown up woman and not so innocent anymore.
You want more change in another major character?
Dick Grayson becoming Nightwing, which was growth driven and not sales driven.
Aqualad becoming Tempest, which was creative driven and not sales driven as this was a supporting character in another book.
Oh, and btw, Aquaman IS a major DC Icon, he was a freaking Super Friend, so his hand still being missing and his baby still being dead are long term changes.
Speaking of Aquaman, change doesn't happen with the heroes only.
Black Manta was altered during Underworld Unleashed to be a mutant Mantaray and he's still that today.
Blockbuster, the dumb muscle from the old Suicide Squad, was turned into a genius... and he's still one today.
Mongul was killed and his twin children grew up and took his place as Superman's enemies.
An upcoming change is Rucka's "Last Ra's Al Ghul" story... we'll see how long that lasts.
Long term change: Mary Marvel's costume following Ordway's series is white instead of red like her brother's. Minor change but long term.
Speedy became Arsenal = long term change. Again, didn't happen because of sales since he wasn't selling anything, he was a supporting character that was allowed to grow up and change.
I mean, think about it. TEEN Titans was a best seller, so making them grow up would go AGAINST sales driven storytelling, right?
It still happened and wasn't undone.
If it hadn't been for Berganza destroying the Superman franchise, another long term change would have been Hyppolyta being dead and Paradise Island being in the Bermuda Triangle, but since because of what Berganza's doing the events that lead up to that MIGHT be undone soon, those changes MIGHT vanish... if they don't, then they count on the list.
Another long term change would be Byrne making Hyppolyta the WW II Wonder Woman.
Unless you decide that it's not real change since she's just replacing Diana in the role...
If I come up with any more and you remind me I'll post them...
Comics are like a Rorschach test; everyone has a different opinion on what they are and can be...
