Early this year Blizzard explained the declining player numbers with players consuming content faster these days. And I agreed. But I think they didn't understand why players are consuming content faster these days.
When Blizzard talks about content they mean dailies and raids, in short: narratives. And if narratives are your content, then more content won't help all that much, Blizzard. Of course, more narratives will help short-term. And should you manage to create like ten times the content per year, which is easily possible considering your profit from WoW, content would solve many of your problems.
However, increasing your content production speed by like 50% or so, won't help much, if at all. It's not like players magically started to consume content faster since mid-WotLK. There were reasons, and players being more experienced is only one of these reasons; and a minor one. Many of us have been 'experienced' for years now.
The reason content doesn't last long these days is the missing community. In a guild with friends I don't care all that much if I wipe many times in front of a raid boss or a dungeon boss. I am busy explaining things to people and as long as they appear to be listening and trying to succeed, I am absolutely willing to wipe many times. Even if I am not leading the raid and just eating my meal in front of the screen while the raid leader explains the encounter for the 10th time, I don't have much of a problem with it; at least not the kind of problem that would make me get bored with WoW per se.
This is different with random groups. My tolerance for failure with random groups is very low. Actually, it's zero. While I am a very nice player in a community, I turn into a sarcastic, elitist player in a random group. And I am not even ashamed for it. I behave according to the social environment which, in this case, I despise. Is my behavior really that hard to predict?
You will find out, Blizzard, that the LFR's biggest problem will be that people have no tolerance for wipes. And that turns raiding upside down! Raiding, when you look at what players actually did most of their time, was all about wiping!
But in a random group, you need to make the encounters really easy. And then, obviously, players consume the 'content' faster and get bored. You could also say: being socially invested in a community makes players have fun while engaging in time sinks. This doesn't work outside of a community.
Now, the obvious solution would be the same you used before: Turn bosses into dailies. Only one boss kill (boss loot) per day. And that, once again, would solve the content consumption problem by making the game worse.
You could also word it this way: When in older MMOs developers found out, to their surprise, that players would stay subscribed although they spent 90% of their time wiping on absurdly overpowered bosses, they started printing money. Producing this kind of content was very cheap and kept players subscribed for months, sometimes years.
By replacing communities with random groups, you are destroying a critical element that made this work. And you will find out that you need to produce content (narratives) at the rate at which a television series produces narratives, if you want to keep players subscribed. Probably, even faster if you don't want players to unsubscribe during cliffhangers.
Your hope that players who do LFR raids become 'normal mode' raiders later on, is going to be dashed. The kind of player who is going to use the LFR is not the kind of player who would do the same content at a harder mode for a slightly higher itemlevel and at the 'cost' of considerable socializing. Only very few players actually move to a harder mode of the same raid to get slightly higher item levels until the next patch. Haven't you learned that from the experience with 'heroic mode' raids?