At least in the mid-west some of the volunteer driven conferences are starting to get bigger because they are cheaper and aren't vendor focused. Check out the CodeMash conference for instance. It's put on by a complete volunteer crew. At the 2009 conference they had a "Precompiler" day where you could learn about .NET, Python, Ruby, whatever from people that were very talented. I think these are the types of conferences that Scott B. is referring to when he said non-vendor driven. Note that these types of conferences DO exist in the U.S. already.
Check out: devlink.net, codemash.org and codestock.org. All three are conferences I'd recommend. Oh, and Ted Neward, Richard Campbell, Scott Hanselman... those big names? Yeah, they were at some of these too. And unlike the PDC, I was able to sit at the bar and listen to Richard tell awesome stories. I was able to see Ted sit in an Open Spaces session and give his opinion.
Personally, I think that instead of these massively large conferences, perhaps more frequent and much smaller (say 500 to 1,000 attendee) conferences that are not vendor linked are the future. Then it won't be the death of the professional speaker. It will be the rise of the regional talent with some of the professionals in to add their experience.