I think that the best way to accommodate all play styles is to do exactly what they are doing now.
Start with a very light tactical game that incorporates the most iconic features of the various editions, then create modular rules and options for more character customization, tactical depth, alternate spellcasting systems and so forth.
It would be a lot more difficult to build the system the other way around.
That's sort of what happened with the 4e Essentials line. It was offered as a tactically lighter version of "core" 4e, with a nod to more traditional iconic elements, but it apparently satisfied very few people in either camp.
I can't blame Wizards for trying to get the horse before the cart this time.