I think it's safe to say that maturity for today's cards will not be the same for older cards. By your theory, the 1970s cards, those including the RCs of Ken Dryden, Guy LaFleur, Denis Potvin, Mike Bossy et.al would be at their highest point. None of those four players could be denied to be in the top 100, if not top 50 of all time, even in the context of players today who are passing their production numbers (though not Cups etc.)
None of those players have seen marked increases in collectability, perhaps save for the Liberal political nut who now loves Kenny D. Even their returned presence in the hobby through jerseys and autographs, again save for Dryden, have led to more collectors demanding the older product, and most of their current stuff can be had fairly resonably.
Why is this? Simple - collectors today are all about the "now" factor vs. the investment. eBay culture has led to a card's maturity, save for a precious few uberstars like Crosby and the occasional hidden gem like Martin St. Louis, coming in the period of a single year, and often one RC decreases in demand when another product hits store shelves.
There are a scant few sets that retain their value or show an increase by year's end - Upper Deck's Young Guns, SP Authentic's Auto'd RCs and The Cup RCs are virtually the only ones that maintain standing in the hobby. A Black Diamond RC at season's end is not nearly as in-demand as it is at All-Star break.
The other factor is this - everyone who collected in the late 80s and early 90s likely still has their cards; perhaps it's in a shoebox in the attic or tucked away somewhere, but the vast majority of us still have them. This was evident in two recent card rises - the 91-92 Barilko Pro Set and the 94-95 Pinnacle Sylvain Turgeon.
In both cases, there was a spike in interest when buzz was created (in the Turgeon case, it was the affirmation that one Patrick Kane was on the card). However, collectors soon dug through those long archived cards and said, "hey, I have this; cool!" Those purchased and sent value and interest skyrocketing were by the non-collecting community who wanted something unique.
For cards like the Roy auto and others, the key is not age - it's rarity. It's safe to say that there were in excess of 2,000,000 packs of Pro Set produced that year. with a run of 1,000 copies of the auto, or 1:2000. Getting the card when we were kids was an impossible dream. Now, though, that we have some money under our belt, as you say, we can now afford it and can pursue it. Thus the interest, and sales value increases.
You won't, though, see that value increase for Roy's RC, because by the mid 80s, the book value factor had been well established, and even if a kid liked a card the same way they did a Star Wars figure, they were never, ever going to part with it. They may play with it, put it in their bike spokes or shoot tennis balls against it (as I did with my cards), but they kept them nonetheless.
For these reasons, cards from the 70s, 80s and 90s will never reach the maturity levels or percentages that those of the 50s and 60s did. Whether Gretzky's records are broken or not, his cards will remain intact at their current $1,000-odd level for years to come. Whether Martin Brodeur breaks Roy's and Sawchuk's records or not, his RC will never sail higher than $25.
