I like the idea of a seperate forum for 4e, as right now, it is all speculation.
Just before 4e news hit, I was having some really cool discussions on Dark Sun. Now that the news hit, I make a post about DS, and within minutes, it's knocked off the page.
I can understand 4e speculation, although I really don't want to take part in it (since it's really just saying "what if...?" and talking about something that is obviously going to change a lot in the next year).
I'm fine with leaving 4e in general, and then creating an "earlier editions" forum or something, where I can have my discussions, although I think knocking 4e to a speculation forum (if even temporarily) would work great.
But I don't think it'll tone down, at least too much. I think, as time goes on, speculation and commentaries are just going to increase.
And if ENWorld is just going to be 4e speculation for the next eight months, I don't know what I'd do.