I was just reading Justice Society #11 and I realized why they introduced this new, darker, Superman into the mix. When this Final Crisis non-event eventually comes around, they are going to need someone to suck it up for the more moarally indecissive heroes and kill Superman-Prime. Having a Superman with no continuity ties to anything else is the perfect solution. He can kill Prime, solve everyone's problems, all the main heroes can wax about it morally and then move on no worse off for the experience. They can even have Superman-22 die in the process so they won't have to waste time having anyone give him grief about killing a character they should have killed two years ago when they had the chance!