I don't see infinite possibilities. I see very few and they would all require a conspiracy between the West and the radical Muslims. Last I checked, we are at war with each other.
Here's the way I look at it. If OBL is dead, then either the U.S. Super Double Secret Intelligence is behind all these "fake" tapes, or Al Qaeda is. SOMEBODY is feeding these "fake" tapes to Al Jazeera and the supplier would have to be US or them. Remember, IF OBL is dead, his AQ supporters KNOW IT. If WE were the source of the "fake" tapes, AQ would KNOW that they are fakes of a dead man and KNOW that they aren't producing them, so they would KNOW that they are coming from US. Why would WE produce "fake" tapes when we KNOW that they would KNOW that they are fake? That makes NO SENSE, WHATSOEVER. And what purpose of ours is served by producing "fake" tapes to keep OBL "alive" when he's really dead? Wouldn't we be better served by announcing that he's dead? Wouldn't that be a great victory in the WOT? Does Bush look weaker or stronger with OBL alive? That's a no-brainer. Again, if we are producing these tapes, we are obviously orchestrating a conspiracy. Al Qaeda would be complicit in the conspiracy by their silence. Has AQ or any radical Muslims cast any doubt on the tapes or had anything bad to say about them? NO! Why is that? Quite obviously, it's because they believe they are genuine. To suggest that they are remaining silent to help us pull off this charade is ludicrous. Again, it's not even a question of whether we could "fool" them into believing the tapes are real. If OBL is dead, they KNOW for a fact the tapes are bogus.
The other possibility is that OBL is dead and that AQ is behind the tapes. There are many reasons to believe that this isn't the case. First of all, we give WAY too much credit to AQ to think they could pull off fake video and audio of OBL. These are cave-dwelling desert rats, not Hollywood film makers. Would they risk putting out "fake" tapes? No way. For all they know, we could easily determine the authenticity of a tape, disprove it, and make them look like complete morons. I don't think they would take that risk if they were even capable, which I don't believe they are. But for the sake of argument, let's assume that somehow they have made these "fake" tapes and put them out. The CIA has not said a single one of the OBL tapes are bogus. They have authenticated them. Do you really believe that AQ could produce good enough tapes to fool our best intelligence? You would have to assume that AQ knows exactly how our intelligence experts authenticate voices and faces and how to defeat that. Do you give AQ that much credit? I sure don't. So, that leaves us with a single possibility - AQ is producing "fake" tapes and the CIA knows they are fake, yet continue to "authenticate" them, making themselves complicit in this conspiracy to keep OBL "alive". The question then is obviously, WHY? Is it possible for all the experts to collude like that and for that to not leak out? NO WAY. Again, we are back to the question of FOR WHAT PURPOSE? How does it help US to keep OBL "alive"? It clearly doesn't! Bush said he wanted him dead or alive. It would make NO SENSE, WHATSOEVER for us to keep him "alive" if we know that he's dead.
All of these "fake" tape roads lead to a dead end. No, we aren't in a conspiracy with AQ to keep OBL alive. The tapes are real, OBL is alive, and the hunt continues. Sometimes, things really are what they appear to be.
Many alternative approaches to the question can produce many dark scenarios, not all of which need be vast conspiracies. It might be just a couple of guys hatching a plot while killing off a few gallons of wine.