Toy cars go for a bomb on ebay. My husband collected them too, well into adulthood. The more unusual, or old in good condition, the better. I've no idea what will happen to them all eventually, I imagine they'll be given away. People collect things because they like them in the here and now and it's only later in life that they think, "What will my (heirs) do with this lot?". Well, that's their problem.
My cousin aged 77 has kept every Christmas and birthday card she has received since she was a kid - can't begin to imagine what will happen with all those.
I think it is a good idea to declutter while you can, something I intend to do. Some of my things (and the old man's), may be of use to someone else and it seems selfish to hang on to stuff I no longer use or even look at. I'd be happy to have it sold on my behalf.
However, nothing wrong with having a few nice things around while we can still appreciate them.