The Perennial Problem
I'm not talking about the concept of endless microtransactions, where players buy cosmetic improvements, experience multipliers or better equipment. Those methods just don't appeal to me unless it's a completely free MMO, and many that I play are not. A lot of the joy I get from playing World of Warcraft is due to its extreme level of polish as a game. I wouldn't want to simply buy equipment in WoW, as a large part of what I enjoy about the experience is playing through content and slowly earning new loot.
The first 60 levels of grinding that my friends and I have done on different servers, or on different sides of the game (Horde and Alliance), are what has killed our ability to enjoy the game. To be honest, I've never even managed to get to level 60 in WoW. My Human Mage is still sitting on the Feathermoon server at level 57 or so and I just can't bring myself to grind up. Even if I managed to do that, all of my friends wouldn't be able to play with me as it stands anyway.
In fact, they wouldn't want to play because of that same grind to 60 that either they or myself would have to face in order to be able to play together.
Some of the best experiences WoW can give you are the ones where you and three or four friends play together in a static group. However, all of my friends (myself included) have played out the original content. We would only be interested in coming back to Azeroth in the event that we could start with a level 60 character and jump straight into the Burning Crusade content.
So why not offer separate servers for players interested in spending 20 or 30 bucks on a new level 60 character, as Mr. Zenke suggested? They could start out with appropriate gear that's just strong enough to handle the content at that level.
The Simple Solution
This is the part where I think Michael lost an opportunity to point something very important out. Instead of locking a character at level 70, the key to my version of this awesome idea is to allow players to start at 60 and experience the game proper from there on out. If this were made to be true, anyone could throw together a five-man static group and play through both Burning Crusade and the upcoming Wrath of the Lich King with any of their friends. Hell, most players who have missed out on this content would probably pay for a couple characters, as everyone has at least two classes they really enjoy playing.
Suddenly, everyone would be playing WoW again -- or at least a lot more people than even now. It's possible that a feature like this could bring a surge of players back into Azeroth as it would allow everyone to start on even ground again just like when the servers first launched. Blizzard really doesn't have to worry about content running out, as there's plenty 60-70 content to play with and Wrath of the Lich King is easily coming out within a year.
I can hear all the people who've spent tons of time playing World of Warcraft complaining about this. "What about all the players who've invested all this time in getting to max level?" are the kind of arguments I expect. Well, what about them? It's not as if potential players were going to grind up so they could come and raid or PvP with those characters. You're not losing out on us having our own sever to play on.
Sooner or later most people are going to stop playing WoW, so it's not as if time spent playing is any less meaningless in relative terms. What matters most is experiencing something fun with friends. Nobody is forcing anyone to pay 20 or 30 bucks to get a level 60 on a special server. Everyone can still grind up to level 60. There are just some who would prefer not to, which isn't all that different from how things are now.
Like I said, what matters most is playing something as fun as World of Warcraft with all your friends. It's what keeps people playing the game in the first place -- with a little help from the grind. By going this route, Blizzard keeps some grinding -- albeit in some of their best zones and instances -- while giving friends and family a reason to come back to Azeroth if they've previously left.
This is an everybody wins scenario, even for those players who've been putting in the hours to grind up to level 70 over and over again. Why? Because they wouldn't have to anymore, unless they wanted to. Somehow, I get the feeling they'd rather be able to throw down 20 bucks for the chance to play with all their old friends who have since left World of Warcraft for greener (or possibly bluer?) pastures.
And really, isn't the best thing about MMOs the chance to play with people you want to be playing with?