On balance, you have cards like Death Wish and Golden Wish that have consistently proved too expensive for realistic play. Golden Wish costs five, and we don't generally play cards that cost four or more that don't win the game all by themselves (and a resolved Golden Wish might not even guarantee a game winner). As for Death Wish... Its life loss is one of the scariest drawbacks ever tacked onto a card. At the very least, if you are the kind of guy with a Death Wish... Let's just say you had better hope the opponent isn't playing beatdown. Due to the success of Enlightened Tutor and Vampiric Tutor, historical analogues to Golden Wish and Death Wish—even with their associated concession of card economy—I'm certain that if the costs on these two cards were less directly prohibitive, both Death Wish and Golden Wish would have found homes in their Heartbeat, their TEPS, their Loop Junktion decks. Basically, any Wish that you can realistically cast not only demands room in competitive lists, but contributes to exciting, winning, decks.
In Future Sight, the playable Wish list gets one
Glittering Wish is both less and more focused than some of its viable predecessors. Glittering Wish is less focused, less restricted let's say, because with this card you are no longer limited to only one or two card types (only instants, only sorceries, only creatures or lands), as you are with Burning, Cunning, and Living Wishes. On balance, you can only grab gold cards. An interesting place to start trying to figure out how Glittering Wish fits into the universe is by comparing it to Dissension counterpart Supply. In a sense, this card is very similar to Supply. It takes a Wish-look (rather than a traditional tutor- look) at Demand... but with the mana cost of Supply!
Supply was a tournament mainstay last summer, both facilitating the Dovescape hybrid deck in Standard and contributing to various tier two Glare of Subdual variants in Ravnica Block Constructed, where it fetched Sky Hussars, Grand Arbiters, Simic Sky Swallowers, and singleton copies of Congregation at Dawn (which would in turn find Three Stupid Elephants™). To be fair, most players were also interested in the Supply side, especially once they had Dovescape or Glare of Subdual in play.
Moving the model from "tutor" to "Wish" does something very specific in deck design. When the intended target lives in your sideboard instead of your main deck, you don't have to jank up your main deck with whatever terrible singletons are only good in certain matchups. While you technically still spend deck space—and more premium deck space at that—at least you can't accidentally draw an off-matchup hoser. A longtime criticism of the "Silver Bullets" strategy was that you could rip Perish against Accelerated Blue or Engineered Plague against Replenish. On the other hand, you don't have as versatile a 75 card deck over the course of a three-game match or an entire tournament.
One thing that is easy to overlook is that Glittering Wish is also a kind of faux Golden Wish. Sure, the number of relevant enchantments is much lower than with a true Golden Wish; true, you can't look up artifacts at all, but this card nevertheless circumvents the prohibitive mana cost associated with getting any enchantments. The possibilities for slight enhancement are numerous and, in many cases, would not greatly disrupt a deck's sideboard plan the way a dedicated Cunning Wish or Burning Wish sideboard might. For example, there are numerous decks that run one or two Dovescapes or Debtors' Knells today. Might they have room for a second (third) copy in the sideboard? Might they play the singleton in the sideboard and have more reliable access to it in Game 1? With four—heck, with two—Glittering Wishes, a player will actually see his lone long-game enchantment with greater regularity in Game 1 without actually playing one main then he would pre-Future Sight!
Despite being named for it as a particular card, most Mirari's Wake decks only played two copies of the one-man Mana Flare. Decks of this order might love to have access to more copies at will without ballooning their curves. There have been versions of the CAL and the Rock with Overgrown Estate or Pernicious Deed in the sideboard... Glittering Wish would give these decks the chance to run these enchantments—or potentially extra copies at least—main. Ditto on Solar Flare-like variants with Teferi's Moat potential out of the sideboard. We've already seen some minority decks with green over black. Glittering Wish seems like a fine fit, or even splash, for some of these kinds of decks.
I always say that my favorite Magic set is Visions. Some of the best cards in Visions, the River Boas, the Impulses, the Man-o'-War, and Uktabi Orangutans, were inexpensive utility or "fine tuning" spells that didn't cost very much didn't do all that much, but that had really fine effects given how much they cost. Glittering Wish is kind of like one of those classic Visions cards to me. It costs very little, but in this case, it might do quite a bit more. Ultimately, the enchantment aspect is the most exciting part of this card for me. We've seen Wishes that can nab instants, sorceries, creatures, and lands already. This card can still do that (well... not the lands, maybe), picking up every awesome card from Angel of Despair to Voidslime.
Glittering Wish seems like it should prove as versatile as it is inexpensive. It should curve into third-turn Ghost Councils and Grand Arbiters, find the clutch Hide // Seek you need to get your head out from under the water, and maybe even aim a Putrefy in the general direction of an Akroma, Angel of Fury. Depending on how extravagant you want to make your mana, you might even get to blow out Dragonstorm with a Shadow of Doubt... So yeah, Glittering Wish will probably end up facilitating something degenerate or closing the loop on a three-card combo... At the very least, this card is in the right colors to grab Saffi Ericksdotter. That's the neat thing about having something shiny. You press a coin into the open hand of the pauper. You can bribe the foreign prince. Finding the right card for the job in your fifteen to the side should be academic.