Allright, I'm callin' it.
I believe we have reached an inflection point in the growth of Magic: the Gathering.
I think that now is the defining moment of a generation's growth in mtg, and certainly the defining moment of the last decade in mtg.
Just glance at the graph below, from google trends, showing the popularity of the search and news term "mtg" over time.
You can see the so-called "magic renaissance", circled in Green. People have written for a couple years now about the turnover shown in purple, which I've labelled "plateau". I've considered this at length, worrying about the possibility of an apex for mtg (this has been a worry for mtg collectors since the beginning, and must happen one day happen unless humans or their wealthy machines live forever, and even then the heat death of the universe...).
Was the renaissance driven by real new demand, and how much has the "cashing in" on its brands and reprints by Wizards fueld growth as a bubble (such as Return to Ravnica, Battle for Zendikar, and, just accounced Shadows over Innistrad)? I don't have the answer to that question, but the fact that we seem to have just recently flipped from concave-down to concave-up in the search populatity of the game's name for the first time since the beginning of the "renaissance" is a good sign.
A very good sign.
So if this data can be believed, what are the take-aways here?
Well, mainly, cards that are difficult or impossible to reprint will see proportional gains due to the greater number of future players clamoring over the old cards. This means Reserve list cards, all the blue-chip Vintage/Legacy cards, and the rare obscure, old stuff. The incrementally better cards that havn't yet spiked. This was shown to be true as Modern emerged as a new format: Lorwyn and Shadowmoor blocks saw massive proportional gains due to the growth in popularity after their release (and their supply was fixed to pre-renaissance consumption levels).
Reprints are a fact of life for collectors nowadays. However, the ability to reprint grows as the game ages and ripens, so this is of diminishing concern over time. I think Wizards has reprints pretty well understood by now, and judicious reprinting is extremely beneficial to the health of the game, just as apex predators are in natural ecosystems. I think part of what we're seeing now is people coming to terms with reprints as not an obstacle, but an opportunity (for example, revisiting old Planes, like Return to Ravnica and Battle for Zendikar, and, just announced, Shadows over Innistrad). Further, I think Wizards can tell the difference between reprinting an extremelty expensive card whose price is propped up primarily or exclusively by scarcity and not "actual" play-demand (e.g. Fraternal Exhaltation), and reprinting an extremely expensive card who price is proppoed up by a genuine mixture of the scarcity and demand (e.g. Black Lotus).
...just look at the proportional gains there. We really did see about a 133% increase in MTG consumption (if the correlation of this search term and consumption of Magic: the Gathering is valid) from the period of 2009 to 2013, an annual gain of 33% year over year. Though mtg as a whole has been strong for its entire liftime, this is incredible growth, even as compared to the entertainment industry as a whole, justifiably deemed a "Renaissance", and which has been heralded, since it started, as unsustainable. And this turned out to be rather true, on a short time scale of 2-4 years. The evidence of stalling in growth was evident for the past two years or more, but if taken in context to the inflection point that started the "Renaissance" around 2009, then this is the rectification of the bubble-like aspects of that historic period of growth. ...and what always follows in the growth of a healthy economy once a bubble is rectified without bursting? The start of the next round of growth.
I rather agreed with this estimate for the last year or so, and I saw the "plateau" in growth from about 2014 to a few months ago as a moment of truth for Magic in the long-term. It was the recipe for a "lost generation" of mtg sets upcoming in the next few years, if Wizards flooded the engine. This new Google trends data has me very optimistic.
I think we could see another renaissance in MTG in the coming years comparable to that of 2009-2013.
EDIT (3 Weeks after original publication, edited on Nov. 4th, 2015)
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I am calling this prediction as officially as I know how, on my own blog: now is the defining moment of a generation's growth in mtg, and certainly the decade (shown in this latest Google trends data, as Nov. 4th, 2015).. So, obviously, this is the article to introduce you to this blog (the Speculator), and our next-gen brewing and buying experience that is Urza.com.