"There will in effect be no more solo content in the game. That's why there is only five levels. In the expansion, the only critical question will be what guild you chose to belong too.- DeftyJames, in the comments on my Friday post on the expansion
Solo is dead."
"The big picture take away message from Blizzcon 2009 is simple: solo content is dead. The real cataclysm is not to the the physical geography of Azeroth but to the entire game experience. Solo questing as a major game mechanism is finished and guilds moves to the center of the game play experience."-Elnia, posting at the Pink Pigtail Inn
I spend 90% of my gaming time on solo PVE content, I have a blog, and I'm not afraid to use it in thousand-word increments. Shouldn't I be the one writing about the imminent demise of my own gaming style? The answer, like most arguments on the Internet, hinges on how you define your terms.
Will you need a posse like Marshall Windsor's in order to do anything in Cataclysm?
Confusing the Incentive and the Gameplay
Defty's choice to quantify the expansion in terms of levels instead of content tells you where the difference in our perspectives is coming from.
Levels are an arbitrary incentive reward given out for playing the game. The whole intent of the "on rails" quest system is for players to attain their next level at the same time as they use up the content from the previous level. You could implement the entire PVE game of WoW leaving the players at some fixed level and having mobs be higher or lower levels to scale difficulty. Instead, Blizzard makes the arbitrary decision to increase the arbitrary number by your head after you have completed some arbitrary amount of content - frequently at first to reinforce the behavior and then more gradually over time as the Pavlovian reflex has been established.
This does not, however, make levels the purpose of the game; if all you wanted was to see a number constantly rising, you could just get a stop watch and set it down on your desk. The reason why World of Warcraft is more popular than sitting and staring at a stop watch is that people actually enjoy PLAYING World of Warcraft. If this is the perspective that you're approaching the game with, new content is new content, whether it's located at level 1 or the non-existent level 86. It's your choice not to use it, but that doesn't mean it isn't there.
(You can, as Defty does in the comments here, dismiss the entire old world revamp as "just adding some new text to the quests". That's a matter of opinion that no one can prove or disprove just yet. My belief is that merely delivering the areas presented at Blizzcon would represent a substantial addition to the world, and that failing to deliver on the one primary feature of this expansion would have a nigh suicidal effect on Blizzard's billion dollar cash cow. Time will tell.)
The Purpose of Solo PVE
I find the assertions by both Defty and Elnia that guild talents will kill unguilded solo PVE especially puzzling because the announced talents are either focused on raiding (Elnia seems very worried about the repair bill she racks up while solo for some reason) or are things that actually decrease the amount of content and challenge that you get to consume on the way to the level cap.
Slow leveling is a problem if you don't want to be doing solo PVE at all and are just in it to get to the endgame (in which case, you're probably in a guild anyway). Slow leveling is a problem if there isn't enough content to actually get you through the levels. If you are doing the content because you are enjoying doing the content, slow leveling is a bonus feature, not a penalty for lacking a guild.
(Ironically, guilds with very diverse playstyles might actually have an incentive to split up over guild talents, so the altoholics can have the talents they want and the raiders can have the talents they want, etc. That's a design issue with guild talents, though, not solo PVE.)
It is true that solo players who 1) do not spend much time on alts, 2) are strongly motivated by working towards rewards and 3) are not willing to settle for incremental gear upgrades obtained from repetitive content will have a bit less to do than usual in this expansion. The truth is, after the way gear has been handled in the Wrath era, I personally fall into that category. I will spend more time in the Cataclysm era on alts than I have in the past, and I might even spend more time away from WoW.
Even so, I don't see how you get from a somewhat reduced number of zones in the expansion to the conclusion that solo PVE, the innovation that WoW brought to the genre in the first place, is dead when Cataclysm arrives. The content that the expansion does deliver will continue to be the shiniest in the business. I will ultimately see the revamped zones, whether it's on a new alt or running by one-shotting things with a level 85 mage. Spending a bit of time tending to an area of the game that has been largely neglected for the last four years will help keep the game around and delivering more content (including more content for me) for years to come.