I think that Khans of Tarkir will change modern in a big way.

care to elaborate?

Fetches.

That Delve 1-drop remove spell and Dig Through Time all seem Modern Playable. Some in my playgroup think that new force spike will be playable, though I disagree since, you know, spell pierce.

Fetches, I agree with. However, Stubborn Refusal seems pretty nifty in a classic control shell. If they find a way to get rid of your massive beater, counter it for .

In terms of other potential Modern game-changers ... Dijinn Illuminatus + Temur Ascendency + Pact of the Titan might be fun.

Fetches don't really change modern so much as they lower the barrier to entry and thus expand access to modern. The people with money were already running the critical mass of fetches - sure, now they are more likely to run ones that actually bridge the colors they're playing rather than running halfsies, but the decks that were running 10 fetches before will still be running 10 fetches now.

More people playing Modern is the biggest change tho. And combo decks that needed to stretch across multiple colors are now viable.

I don't think you understand how much being able to have perfect mana is important to a format. Having to play off color fetches makes mana for certain decks really awful because if you want the proper colors on time you have to take a bunch of damage rather than being able to fetch out basics if you want. This could be the reason why U/W Control is bad in modern, because you can't fetch for basic plains. Fetches, regardless of lowering the barrier of entry, change the format a lot.

Allied Fetchlands alone are going to heavily impact Modern. I don't know how many of the other cards will really matter (maybe that 1 CMC mill artifact) but even if they don't there will be decks that are viable now that weren't before.

What I'm wondering is what mana bases are going to look like. If they start resembling Legacy more (12-16 fetches, 4-6 non-fetches) then LD could easily become a deck in the format.

For example, Storm now has another 8 fetches it can play if it desires.

They fetches don't matter for decks that already had their colors. It's more for a naya deck now getting two fetches they needed to exist. Or Grixis, because they don't want to take damage from their lands.

I think the deck that benefits most from allied fetches is the Ad Nauseam combo one.

I think I said that earlier on the forums here, but that was what I was trying to get at.

that said, I think storm will start playing 10 fetches, at least.

And Zoo might make a comeback. That'd be awesome.

Edit: Domain Zoo

Why would storm play 10 fetches when they had access to 8 and didn't play 8. That doesn't make any sense.

The basic modern storm is UR, right? Yeh, lists I've seen have been running the 4 UR fetches, plus another 2-3 halfsie fetches (RW or UG). They could already have run as many as 8 of those halfsie fetches but they were voluntarily running far less than 8 - I don't see how the addition of the options of running UW, UB, RB, and RG fetches really changes what UR storm is doing. If they wanted more halfsie fetches they already had the option of using as many as 8, and opted against; adding more halfsie fetches to the available cardpool doesn't change that.

And that was my point in my original post above that people jumped on. So many existing 2-color decks (most notably, opposing 2-color decks like UR Storm; admittedly allied-color decks get better with the modernification of allied color pair fetches) are already running all of their both-on-color fetches and less than the maximum number of half-on-color fetches. They've already established the limit of fetches they wish to use, and it's short of the number available to them now. Adding a different variety of half-on-color fetches to these decks' available cardpool... doesn't change the decks in any relevant way. So now instead of running Misty Rainforests without forests, now they can run Polluted Delta without swamps? That's not relevantly different at all, unless they had already reached the maximum of 4 Mistys and were seeking more. But they hadn't. They were already running at their chosen critical mass of halfoncolor fetches, and adding different halfoncolor fetches to the cardpool makes no relevant difference to these sorts of 2-opposite-color decks.

omg mean girls reference 10/10

And I'm running 9 in storm. 4 tarn 3 rainforest 2 mesa. Then 4 Vents 1 Mountain 2 Island

I'll get to the explanation, but first I'd like to congratulate WotC for printing their first set beginning with the letter K, also sponsored by the number 26.

Where is the x and q sets.

So you're admittedly running less than the max. If you wanted one more islandfetcher, you could have gone to 4 rainforest. If you wanted one more mountainfetcher, you could have gone to 3 mesa. What does adding other islandfetcher or mountainfetcher options to the cardpool do for you? Why would it push you to 10? You wouldn't have played 4 rainforests before but you'll play 3 rainforests and a polluted delta now? To what benefit? Frozen Aether + Sowing Salt combo protection?

My point was that people are running more than 8 fetches in some decks.

This can easily mean that people will eventually start using more if the need is there.

I don't think you know how most people do deck building with fetch lands. Most decks that want a ton of fetches stop at 9, basically. Only deck I can think of off the top of my head that wants more is Burn which plays 10-12.