With the proper Hideaway land ( Windbrisk Heights is lovely ), you could get anything out ridiculously early. If you're prepared to lay down some serious cash, T2 Emrakul could be a reality ( T3 is trivially easy ). Countering would be fairly easy, too ( and worst case, your Emrakul stays exiled ), but ... I think I'd risk it.
Suddenly I'm reminded of why I don't play the older formats.
No, he's not a reality. Unless you're playing legacy and playing Show and Tell or Survival of the Fittest, T2 or T3 Emrakul is next to impossible in Modern. Windbrisk Heights requires you to have three creatures attacking in a single turn - it's a lot more difficult than it looks, considering that this is a format with Lightning Helix, Lightning Bolt, Path to Exile, Pyroclasm, not to mention Remand and Mana Leak to counter your spells, and Thoughtseize and Inquisition of Kozilek to remove them from hand. Believe me, I've run Windbrisk Heights in both Soul Sisters and W/B tokens before, and it very rarely gets set off. If there's a Windbrisk Heights in play your opponent will be actively trying to remove your creatures before they can attack.
And think about it this way - if you don't draw Windbrisk Heights, and draw Emrakul, he's a dead draw forever. It's like Tron sitting there without the Urza lands and slowly trying to reach 7 mana to hardcast Karn - they've most likely lost the game by that point, except instead you're trying to climb to 15 instead. Or what if your Windbrisk Heights hits nothing? Are you really going to play four copies of each Eldrazi Titan so that you're sure to hit something worth using Hideaway on? When I play Windbrisk Heights I'd sometimes never hit anything worthwhile, even when running 2x Elspeth, Knight Errant and 4x Hero of Bladehold - what more a single Emrakul? And if you do run a number of Eldrazi Titans, they're all dead draws unless you have something to cheat them out with.
I think at that point you might as well be running Maelstrom Archangel/Coalition Victory/Omniscience Combo.
Edit: There is also Quicksilver Amulet. I used to use it to bring out Emarkul. Why pay 15 when I can pay 4(think it was.) But it puts into play and not cast. Which, they can't counter since it is an ability and you aren't 'casting,' you are 'putting.' I'll just put this here 15/15 pro all colors onto field. ;o Don't worry, I'll swing next turn with flying and annihilator(what did he have again, six?)
Board wipe. Damnation, Terminus, Wrath of God, Supreme Verdict, Oblivion Stone, Pernicious Deed, Nevinyrrl's Disk, etc. In a multiplayer game somebody ought to have a boardwipe. Or deal with the Quicksilver Amulet/Elvish Piper/Maelstrom Archangel/Cheating mechanism before it has a chance to activate, with things like Krosan Grip or Sudden Spoiling if there's a chance they activate the ability. And even if it's put into play, you can still Stifle/Voidmage Husher the ability. If he's cast you can still Mindbreak Trap or Time Stop. You can also kill Emrakul with creature or artifact or enchantment abilities, so Nekrataal, Royal Assassin, Intrepid Hero, Shriekmaw, Executioner's Capsule, Spine of Ish Shah, Oblivion Ring, Detention Sphere will all kill him. Alternatively you can keep him locked down with Ajani Vengeant or Tamiyo, the Moon Sage or Citadel Siege. If my opponent got to fifteen and all he has is an Emrakul instead of going infinite with Exsanguinate or Hurricane or Debt to the Deathless or Helix Pinnacle, I'm pretty happy, because so many normal cards deal with Emrakul. Just because you can't Path to Exile or Counterspell doesn't mean he's difficult to deal with.
Edit II: I will probably do something with Hideaway for casual play. My only real competitive deck(which I won local modern tournaments with) is my land hate modern deck which again, has a high potential of T1 land destruction and if not, guarantee by turn 2 I will be popping lands. I beat pod before with it, before pod was banned.
Could I have a look at the decklist, please? I'm really curious at how the deck works - T1 land destruction, as hard as I think, I can't imagine being possible.