WotC prints mechanics that become useless before they rotate out all the time. In fact, they prefer to do that, because they don't want you caring about last year's mechanics, they want you excited about the new stuff. Enemy fetchlands are not happening before BFZ rotates out, people really need to stop giving themselves false hope about it.
False hope is what some people need.
That places the earliest time we get them at what, spring 2017? About the time when we'd get Modern Masters 3?(Assuming 2 years between MM releases) If that's the case, I wonder if we'll just not get them in Standard any time in the near future.
Khans was Game of Thrones (most popular nerd TV show) x Gold (most popular Magic set theme by a huge margin) so... I don't think this conclusion is particularly well-supported.
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KTK is nothing akin to GoT, because GoT was fantasy based in ideas that was already super established in TV/Film(European focused fantasy) . That's not to say that we don't have non European aspects in GoT, but 99% of the show focus on characters and/or places that are based in European fantasy.
KTK was an Asian inspired set design wise from a company who had made a mediocre Asian set to a consumer base that had rejected it*. I know that there's a vocal portion of people who like the set, but I've heard that it's considered a dud by a lot of players. There's every reason to believe that the set could have been a flop. The Allied fetches helped to mitigate this by selling what was a hard sell with a modern reprinting of Ally Fetches.
*I'm basing this on what I've heard of the block as a whole from people at my LGS/The Internet.
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With how much Gideon is right now, I'm coming to the decision that if I crack a Gideon I'm selling him ASAP. Sure, he'd be nice, but he's $45 in Canada and I'd have to dump $180(He's an auto 4 of since he's so easy to use). Like, I get that Magic is a middle class hobby, but these current Standard prices are just wow.
If you're running UW, just the Fetches/Santas/Planeswalkers runs you $600 on Channel Fireball. Sure, you can knock off $200 if you shop well, but that's $400ish for 14 cards.