Imagine that the entire expansion is ALMOST EXCLUSIVELY DUNGEONS AND RAIDS; so for example the first "zone" is 5 to 10 dungeons and 2-3 small raids and you go on like that for like 5 zones and it's all dungeons and raids all the way and in the end of the first patch you get a giga-raid which may also expand itself as the expansion unfolds (e.g. imagine if WotLK had a giga-Ulduar that kept opening new bigger wings in it every single patch until the end of the expansion).
And it would also remove the main problem we face today as people that mainly care about optimal raiding (and the pvpers are together with us at that); we don't give a shit to do mundane daily and weekly tasks in the open world in order to have an optimal character; the devs' excuse is "casuals like it" but casuals have plenty of open world grinds already and they don't have to contaminate the hard core world with it too.