Nothing, I think, except for my own philosophical evolution that contributed to getting rid of this collection. I don't think I'll ever collect anything for the sake of collecting again. If I start another collection, I think it will have to be something meaningful. For example, I was at a professor's home when I was visiting Miami in January. He had a really cool collection of unopened Coke bottles from about 25 or 30 different countries. But he's not out to complete a collection of international Coke bottles. Each bottle represented his trip to that country (with a few exceptions where friends gave him one as a gift from a country they visited). I could see doing something along those lines. But I suspect that I am done with collecting just to collect--gathering up things for no other reason than to just have them.
I mean, I'm not going to live a spartan life. There are any number of reasons to own something that isn't useful--aesthetics, sentimentality, etc. For example, when I got rid of my book collection, I kept a couple of signed Vonnegut novels I have. Because I love him and those particular books are special to me. But just collecting to collect, I'd wager I'm done with it.