The idea of value and what will be worth money in this hobby 10 years down the line is a question and that is fundamental to collecting, well to most of us. A lot of us are more than willing when we have that extra money lying around to go down to our hobby shop/ebay store/target etc... and drop some coin for a chance to get that big hit, that last card we need for a set and so on. I'm no different - I've already busted 3 boxes of 2009 product. I've started arranging trades to finish those sets up, and hopefully I will be able to help other people hit that same goal as well.
Now of course as much as the next one, I don't like seeing something I paid $80 for all the sudden being sold for $35, but it happens. We all know about those cards from the late 80s and early 90s that carry almost next to no value now. So yes, while that stinks for a lot of us who were hoping to retire off of all those Albert Belle rookies they are now just want list filler. But I have to say I owe my currently being back in this hobby to those boxes of junk wax.
A few years ago I was super bored, went on ebay, and bought a lot that had boxes of 90 Donruss, 87 Topps, 89 Score. and just like that - I was back - It took a while - almost a year and half before I even considered buying new product - which I now do more often than I would like.
I sort of went off topic. I wanted to talk about why I did not participate in the bat around, and while I write this, I realize I probably just should have used this answer for that -- (disclaimer - I really did enjoy reading what everybody had to say on the topic). But for me, I understand that for some people this is their job and this is how they make their money. But the idea of value and hobby for me are counter intuitive - I do this because it is fun. I enjoy looking through the cards, putting them in order, chasing down a set, and all that goes with it. If I get a card thats "worth" a lot of money - it goes in the same box as my Hunter Pence rookie - sure one is worth just about nothing and the other could be "worth" a few hundred bucks - but that means nothing to me. These are cards that I will hang on to because I like them - if nothing else, they get to be trade bait if i see some cool Mets stuff someone else has opened.
While its good for some people - it doesn't rub me the right way when I see links to your ebay store on the page. there have been times in the past where I see someone working on a set so I send some cards or sps their way (of course they send something back, so I know I do not have a leg to stand on here) but then I see those cards on E-Bay a few months later. I view it like if you have a dog you need to get rid of - you want to send it to a nice a home where it will be loved - not brought to a puppy option.
I didn't really plan this post out well - I'm just writing off the cuff - and maybe I sound like a jerk off or maybe I've made sense to someone - hopefully it just made a little sense at all to anyone. But to answer the question of what I think is going to be worth having in 10 years - I answer who cares whats valuable so long as you have something that you love and enjoy