Without Eye there is interesting space to explore with regard to Modern Eldrazi, and there are still configurations that enable turn two Thought-Knot Seer. That said, the older iterations of Eldrazi hinged on mulliganing into a two-mana land---going forward you can expect Eldrazi decks to be more fringe and/or just light on actual Eldrazi spells.
Meanwhile, two potential juggernauts are being introduced to Modern for the first time:
Already we are seeing lists pop up with one or both of these "new" tools, and already it seems clear that their impact on Modern will be more significant than, say, the unbanning of Bitterblossom.
One mistake I've seen with regard to building Thopter Sword decks is players just jamming both pieces into a deck alongside spells that have nothing to do with the combo. This worked for Splinter Twin, but Thopter Sword provides much higher upside when you build with the combo in mind.
The long and short of it is that as long as you have any artifact to sacrifice to Thopter Foundry when you find it, you can do so to get your Sword of the Meek back from the graveyard. This makes sacrificing or discarding the Sword "free," and improves the power level of cards that do so. The most common historical example of this was discarding Sword to Thirst for Knowledge.
Alternatively, you can use Tezzeret, Agent of Bolas to turn your sword into a 5/5 to threaten to win the game on its own while Tezzeret digs for the Foundry.
Tezzeret has already spiked significantly, though he's just an example of one approach. It's unclear that a Tezzeret build is actually the best way to feature Thopter Sword, considering that its matchup against Ancient Grudge can be rather dismal.
Make no mistake, you'll want to have non-Sword artifacts so that you can safely bin the Sword, you just don't want to go overboard. Something as simple as including a couple Darksteel Citadel in your deck will do the trick. Maindeck Engineered Explosives are also just generally good to have while also fitting your "any artifact" requirement to get the Sword back the first time.
Meanwhile, the other decks that showed up to PT Oath of the Gatewatch will be the obvious fallbacks for the format. These include Affinity, Infect, Burn, and Suicide Zoo. For all of these decks, the goal will be to win before they're buried by thopters or Ancestral Vision comes off suspend. If you build your Visions or Thopters decks without enough cheap interaction, then you'll find yourself in the losers bracket in short order.
You can fully expect these staple decks to start showing up again, and speculation targets for them have been pretty well documented on this site.
If Death's Shadow becomes the aggro creature of choice, then it definitely has room to grow from $6, a very likely outcome in the near future. Death's Shadow plus Temur Battle Rage can shake off quite a few thopters if your opponent doesn't have a removal spell.
Another card that is about to be excellent again is Kolaghan's Command. It beats up on Affinity and Infect, breaks a Thopter Foundry, and gives you value to keep up with Ancestral Vision decks. I fully expect there to be a good Grixis shell with Snapcaster Mage out there---a deck which definitely benefits from Tron losing Eye of Ugin.
A Grixis deck could also jam Vision and Thopter Sword on top of this, which sounds like a great place to be. I don't know how much room K Command has to grow with it already being a $16 Standard-legal rare, though Snapcaster Mage is coming back to Modern in a big way. I expect it won't be long before ol' Snappy starts climbing in price.
Another interesting idea that I had for Modern revolves around Glittering Wish. The idea is still in its infancy, but the long and short of it is that Glittering Wish can find both Jeskai Ascendancy and Thopter Foundry.
When Thopter Foundry was an Extended force, the best list also featured access to the Dark Depths/Vampire Hexmage combo. Access to two combos that are relatively difficult to disrupt puts a lot of pressure on your opponent to draw the right cards at the right time.
Both Jeskai Ascendancy and Thopter Foundry fold to Abrupt Decay, though beyond that their juxtaposition leads to two win conditions that are relatively difficult to interact with. It's definitely nice that Ascendancy can't get hit by Ancient Grudge, too. It's a rough sketch, but something like this is worth exploring:
The mana definitely isn't perfect, the exact mix of cantrips probably needs ironing out, and I don't know that Darksteel Citadel is necessarily the best backup artifact for the first Foundry activation. But I think there's something here.
Having access to five copies of Thopter Foundry with four tutors is pretty stellar, and Thought Scour can flip over Fatestitcher or Sword of the Meek to get either combo going. I'll admit that I'm not the best person for building decks like this, though theoretically there is a shell for a resilient and explosive combo deck here.
Glittering Wish once pushed $20, and if a deck like this breaks out then you can expect a return to that price. A couple sets of Glittering Wish is a gamble I could get behind.
There will be a reasonably sized Modern tournament near me this Saturday, and I'll be battling with old reliable. It's time for Grixis Delver to make a comeback, baby! It's hard to say exactly what will come out on top this weekend, but given the short time frame to prepare I think four copies of Spell Snare will do a great job of keeping Thopter Foundry at bay while Tasigur beats down.
I liked the deck against the expected field pre-Eldrazi, and my only concern with these unbannings is losing long games to Ancestral Visions decks. I don't like the idea of playing Visions in Delver, because I think it's a liability everywhere except against the grindy decks, though I have a plan for a transformational sideboard:
It's a bit generous to call it transformational, but the plan is simple. If they have Visions, Delver goes out and Visions come in. I was already boarding out Delver against decks that were adept at killing it, and this is a significant upgrade.
It might turn out that I'm just supposed to maindeck the card---this is what happened with Kolaghan's Command, after all---though this will be my starting point this weekend. I have some concerns about finishing three-game matches against Visions decks, though we'll burn that bridge when we get there.
It's unclear just how safe the unbannings were this go-'round for Modern, and it will be pretty exciting to see how things shake out. Whether you decide to invest in the established or the up-and-coming, the players who quit Modern for Eldrazi winter will be returning to the format, and you can expect increases in the pricing of the Modern format in coming months.