Re: Luke Cage introduced in Avengers 2, Hulk blasted into space
Cage still needs to be a willing participant. Think if Banner was a criminal and an unwilling participant, and through experimentation became Hulk. You're boned. It's the same thing in this scenario with Cage but to a lesser extent.
Of course Cage will have ulterior motives if he is an unwilling participant. That's why it's stupid to give someone who is not on board with the plan, powers that will make them unstoppable. If AIM is so genius they should be able to figure that out. Out of a prison population, you would have a ton of psychopaths who would do anything for super powers and freedom. You don't pick the guy you have doubts about.
Giving Cage a history of incarceration and gang activity lends credibility to the idea the prison would experiment on Cage. Any good scientist would test on multiple subjects, a prison gang perhaps? These experiments could tie in with AIM and extremis (I thought that was a given considering AIM's involvement) but there doesn't have to be deaths from the experiments because extremis in IM3 hasn't shown to cause any.
To put Cage in prison he was falsely accused and wrongfully imprisoned. Upon Cage and Wrecking Crew's breakout, Cage begins to hunt down the actual felon. This should be another super villain and it's possible they are working for AIM. Maybe Iron Fist and/or Jessica Jones has been looking for this guy while Cage is imprisoned. (Pick a villain as I don't read the comics and am unfamiliar with Cage's/H4H stable.)
EDIT: Reading wiki, Purple Man could have made Cage do the crime he thinks he is wrongfully accused of. That would shock Cage and the audience. In the scenario, Purple Man is just a dude, not connected to AIM or anyone, yet.
It won't surprise me if Jessica Jones is never given powers. From what I have read she seems too similar to Cage in types of powers and that would need it's own bit of explaining. She could be a street gang detective who knows Cage from his history of crime. At the end of the film, Jones leaves the force to join Cage and Iron Fist in Heroes for Hire to track Purple Man and the remaining members of Wrecking Crew.