I will hold on most everything for now. I'm selling off some pieces that don't fall into my area of interest any longer, just so I can build up a bit of bank for things that do...but I sold off a LOT in 2007 after getting laid off and the recession hit, to keep the lights on and food on the table. While I regret it now b/c a few of those cards (sold for in the hundreds) would be in the high 4 figures now, at the time it was necessary.
I have nothing in hand today that even sniffs 5 figures, so regardless of how much further this bubble expands, I'm standing pat.
But, I too will eventually let it all go as neither of my kids has even the faintest of interest in little pieces of cardboard
There is no wrong answer to your question, which makes it such a great question.
Bill