You do realize that Blizzard's early onset success was due to a "right place at the right time" mechanic, which has nothing to do with what models they used or how they marketed the game, right?
Wow's success was almost perfectly timed with an era that had a lot of ex-mmo players looking for a new one to play and also introduced the more casual game players into an online alternative that worked well and was "seamless". Their largest sub climb, in TBC, was due to the game still being fresh and new to so many players and it took a long time for them to level.
However, as you can tell by the 24 month spiral of subscription losses posted at almost every quarter, the wow model is not the perfect model, nor is it a model that will help retain old players or attract new players, simply because the conditions for their mmo to shine have all but faded, and many, many other high quality mmo's have hit the market.