The difference is simple: Bliss sees a battlefield as a fluid environment with surprise developments and multiple time scales whereas the fans of the old Coop format
essentially want a team-based "Meet in the middle and let's have it out there". That has a lot more similarities to a sports match with a level field and a defined starting point, though.
I doubt we will see a Coop format in the way people are used to it. For that the basic mission format of the current engine is too open and universal. It does no longer produce a self-containing "sandbox" for that one mission but provides the basic characteristics of a dedicated server for both offline and online. Changing that back to a "canned format" looks like a very tall order in my uninformed eyes.
