Interesting. Separation of campaign content into ai/hero/map/events could enable a fluid and agile production process, which would be better then the previous waterfall approach.
I hope they unlock a debugging hero and map so that bugs can be ironed out before November 10th.
I think it would be good since this new way of working also means all public test-alpha/beta/preproduction/prod builds are using same client folders and resources.
New and returning customers may have lower patience with regression then dedicates ones. Also I have a feeling the coop mode will make/break success of sc2. You only get one chance to make first impression :)