I think it's all trend related, Don. People see an awesome deck that used metallic inks, see that it got overly funded (in the case of Kickstarters) and want do the same thing. Eventually, everyone is doing it (like you mentioned) and it gets old. Then it goes away for a while and eventually someone makes another awesome deck that tastefully uses metallic inks and everything comes back full circle.
Same with Zombies, Pirates, Lumberjacks (yeah, I said it. Lumberjacks are definitely trendy) etc, etc.
Actually, I think you're still running on the road less traveled, as far as lumberjack-themed decks are concerned!
The trend I'm most concerned with is the trend toward more carelessly-made crap by creators who think that all that's needed are some bells and whistles combined with an artificially-short number of decks in existence and they can make fat stacks of cash like the people and companies appearing on the list of top ten decks by income on Kickstarter. "Throw some zombies on it, perhaps a steampunk sugar skull, slather it in gold and order only 500 copies, of which I'll only sell 400." This is NOT a formula for big success, despite the existing trend. It's like trying to get on the New York Times bestsellers' lists by printing a few hundred books at a boutique press. I can't see custom card-making as an industry thriving by using such a formula.
I understand the points you're making. I think the underlying meaning is, you're worried for the industry. I also think you're being cranky. 
Those powers combined. 
More concerned than worried, and more fed-up than cranky. OK, maybe a little cranky. I know playing cards in general will be around for centuries to come - there are no forms of gaming entertainment and play that are as versatile as a pack of playing cards. Hundreds of games, if you run out just invent new ones - and it fits in your shirt pocket. And that's before you consider magic or cardistry!
Custom decks, however... This can be a bit more difficult to pin down. But I certainly can't see the industry of custom decks "expanding" by manufacturing fewer units of each deck rather than more. Ours is a niche hobby because the decks themselves are becoming more and more difficult to come by!
The deck that likely began the modern wave of custom design work, the Bicycle Black Tiger deck with red and white pips, is still in print today, largely unchanged since the first pack was made other than tweaks to the stock and coating, the tuck box and swapped extra cards from print run to print run, depending on what Ellusionist is trying to promote at a given point in time. I think one could safely say that many thousands of this deck are in print - over a hundred thousand at the least, over the years. But as collectors, many consider any deck made in quantities of greater than 5,000 as ridiculously common! Nothing could be further from the truth. Assume that 100,000 packs of Black Tigers exist - that means that the typical American (among a population of 400,000,000 Americans) has a 0.025% chance of owning just one pack, based solely on number of decks versus number of people and given a distribution of only one pack per person! The reality being that many collectors will buy multiple packs, that chance drops significantly.
Using the same math but applying it to a "common" deck with a print run of 5,000 yields a result of a 0.00125% chance of the typical American owning a pack (again, the percentage is much smaller when you account for the fact that collectors frequently buy more than just one pack). A "common" deck, and only 1 in 80,000 people have even a chance at owning a pack!
More importantly than my rough math and estimates, consider that this isn't even taking into account the world at large. Going globally, assuming as even a distribution as possible, those numbers absolutely shrivel. As of last year, the estimated world population was 7,125,000,000 people. Not more than 1 in 71,250 people have a chance at owning a pack of Black Tigers, and not more than 1 in 1,425,000 people have a shot at getting a deck from any typical print run of 5,000. Considering buying patterns and attrition due to destroyed decks, I've probably overestimated those odds of ownership by as much as ten times the actual chance, but there's no way I could have underestimated the chances, assuming my numbers are reasonably accurate. But that's "common", according to some people frequenting this forum.
More decks in more hands means more people are interested, more decks get sold, more money gets made, and without having to charge a king's ransom for just one pack! I still consider the idea of a pack of cards selling for $15 or more ludicrous, even with shipping by first class mail included. My city is insanely overpriced and I can still get a pack of plain Bikes for under $5 a pack - aside from the time and trouble spent designing the cards, what makes them so special that they cost that much? Most people can buy Bikes for $2 or $3 purchased individually, no bulk discounts for buying a brick at a time. I understand profit as a motivating factor for making the cards, but taking in a bit less profit per deck while selling a LOT more decks means you can make them cheaper AND make a bigger profit on the project overall.
Yes, a custom deck costs more to make, especially when you go all crazy with the bells and whistles. But are all the bells and whistles necessary - do they improve your project, your design, or do they simply attract people like birds looking at shiny objects? Strip out the bells and whistles and a pack of cards made through USPC Custom can cost under $3 a pack - and probably even less still if you went with LPCC or EPCC. I can make a thousand of them, sell them at $15 a pack, sure - fat profit, but really short supply.
Assuming a cost of $3 a pack, an average shipping cost of $2 per deck and a print run of only a thousand, that hypothetical deck would earn you a total of $12,000. Take that same project, drop the price to $7 but make ten times as many decks - right there you've made $20,000 instead of $12,000 and in the process got more of your decks to more people. Many customers that might buy just one or two at $15 a pack could go as high as a half-brick or more at only $7 a pack.
I can't possibly be the only person who sees the math here. Bigger print runs and lower prices will get your art, your labor of love, into the hands of more people - people who have the potential to become fans of your work and repeat customers for your future projects, making your business GROW to the point that maybe, just maybe, you wouldn't even need Kickstarter anymore to hold your hand while you cross the street to profitability.
