My campaign of 13 years ends sometime in the next month or so as they finally reach it's final confrontation.
After that, I'll do what I've always done, use what I like from everything I've bought to inform further campaigns regardless of edition.
But I'm not going to 4th. I'm swinging into True20 & Omni System territory. Since they are based on 3.x, everything I have from 3rd Edition is still useful in many mechanical ways.
So, I don't have any crap, it's all useful. In fact, I have so many books of so many editions, and from some other systems, that I really won't even need to buy any rules oriented material again.
Thus, I'll be playing with it, and referencing it, and other.