Bane should have been a surprise villain in Asylum
What if, instead of Bane showing up out of nowhere and only reappearing as a cutscene possibility, Bane took over at the end of the game, similar to Origins? Maybe have him take Joker's place as "Jack White," funding the Titan project.
Joker surrenders too easily, frees all the inmates, Batman finds Bane in the medical facility, and he disappears most of the game. They then find out that Bane wanted to be transferred to Arkham Asylum, to find Young's notes and the secret lab in the garden. He allowed Young to use him to facilitate the development of Venom, and reveals himself late in the game. The battle following Gordon's rescue would be unchanged.
Bane would also take Joker's place as the final boss, but in this version, the floor collapses into the original Joker fight — the stealth boss fight that got scrapped for the atrocity they gave us.
It would be similar to what happened in City — Bane appears innocuously in relation to Titan, then reappears at the end of the game in Joker's place, dosing himself with Titan (no need for Batman saving Gordon then rejecting the cure), then, like Grundy's fight, Batman drops into the Titan Joker stealth boss immediately following the action-oriented Bane fight. The mechanics would resemble the TN-1 Bane fight from origins.
Plot: Bane revealed initially just like in Asylum → While investigating Young, Batman finds out she had a benefactor, "Jack White" (Bane insteadvof Joker) → Batman finds goons looking for Young's notes, and learns about the secret lab somehow (probably not Harley in this version, though he technically knew at that point) → Bane in lab, revealed to be Young's benefactor, two-Titan thug fight like in Asylum → Bane doses himself at the end of the game, same as Joker did (minus kidnapping Gordon again), Batman fights and defeats him.
Gameplay: Medical facility fight → Asylum Bane fight → Bane unleashes two Titan thugs in the secret lab → released Asylum Titan Joker fight (combat encounter with Titan Bane substituted) → Scrapped predator encounter Titan Joker fight with TN-1 Bane mechanics, or similar.