The article has a lot of words, but says very little to me. It sounds like a bunch of non-committal corporate mumbo jumbo, that's aimed to make people excited.
First of all, the play test being only pregenerated characters, is very disappointing to me. Honestly, they don't need "us" to test and see if the system works with a bunch of canned characters. They can do that themselves, and see what works, what doesn't. Closed betas are more than sufficient for this process. What they need the masses for, is stress testing. Where does the system break? What are emerging trends in tactics or builds, that need to be examined? Is everyone suddenly playing ranged characters and ignoring melee? Is everyone playing a dwarf? Why does no one even look at playing a halfling? These are the things that need to be nailed down in public play test with a large pool of players. So releasing pregenerated characters for play test is just advertisement and a way to keep people involved, but is not really all that encouraging of a step for system development.
Second, outside of conventions, people rarely play D&D with pregenerated characters. Creating your character is a major part of the D&D experience, and the part that's going to get the most heated feedback.
Third, putting the combat system through some ringer and setting it in stone, is the mistake that 4.0 did. As the system evolved, they ended up having to make significant changes, from introducing expertise feats, to adjusting numbers on all monsters. So the combat system cannot be designed independent of the capabilities of characters.