I'm worried about this too. And i'm not worried about the indicators not existing, im worried about changing established mechanisms of handling open applications. People say that it will just take a tweak to bring the indicators back - but are you sure? I mean, if indeed they move onto a 'every app is running but not running at the same time' philosophy then there's no real way to actually indicate which apps are running, because there will essentially be no difference between running apps and not running, in a sense, no running apps at all. I don't know, maybe I'm old fashioned, but i really like managing myself what's running and what's not. I don't want certain apps to get suspended when i change focus to another app. If i need to, I'll quit them myself. And how would that work in the first place?? I mean, certain apps like iTunes will still need to be running. Are they gonna make it like iOS, like having applications only sending certain data, like audio etc? Just some thoughts on this. I still want to believe that the missing indicator was just a presentation thing and that it's not gonna happen. We'll see soon.
Also, i would love push notifications on the mac, maybe using growl. This way i won't have to run apps like Mail if i dont' need to.