Nope and here is why: The game is impenetrable to new players, leveling is a confused mess (story wise), the zones end up hyping bosses and raids you're very unlikely to play during the initial leveling. Essentially a mass of storylines with no real conclusion. Furthermore, dungeons while leveling would be tremendously boring, last time I leveled an alt back in mists every dungeon group was 5 dps decked out in heirlooms, they were over quick, they were trivial and often with useless loot I had to vendor. I mean, pretty much the same as dungeons at max level, but they aren't much fun either.
I think Blizzard would need to radically change the level range of every old world zone allowing new players to skip outland and northrend entirely (essentially leveling 1-80 on Eastern Kingdoms or Kalimdor) as those two aren't really up to snuff given the experiences we get in Mists and Warlords and allow new players to experience a consistent story while leveling and feel involved in the world. Also end each old expansion with a solo scenario where you beat the big bad with a bunch of npcs, essentially a watered down version of the old raids to give new players a definitive "end" to the continents, like imagine finishing Twilight Highlands and then getting to do a little solo instance where you beat Deathwing and then get the cutscenes.
Also old players are burned out on wow, pretty much everyone who would play wow has played wow and has moved on. What we saw with Warlords was a lot of old players come back to experience the nice looking character models and such, they had a nice trip down memory lane and then left once they had to deal with the boring ass end game. This is a bit harder to fix, if you don't limit what people can do with weekly or daily lockouts for crafting, raids etc then people will burn through content damn fast and if you do limit the players they resent it. No winning. But what keeps people around are communities, good guilds with good people. If players are invested in that, then they are invested in the game, I'm not sure what they can do to better facilitate that, but it really should be the top priority for Blizzard.