In case you haven't heard, there were some goings-on at the MTG panel at Comic-Con this past weekend.
I don't think Wizards is terribly worried about its products competing for the spotlight--it'll make huge announcements while a main event is going on, and annouce multiple things all at once. That leaves it to us to settle out what the heck got said.
They announced that there will be product every year to support Commander, but that includes things like Planechase. Wizards has figured out that as long as they print enough of the Planechase/Commander/Archenemy decks to keep the Legacy crowd happy, creating brand-new cards is possible. This is exciting! I'd guess that the summer of 2013 will have the second coming of the five Commander decks, only with four-color legends, something that we are currently lacking. (Some of you play Nephilim decks, for which I salute your dedication.) That's a bit of pure speculation, but you heard it here first!
I think that the Return to Ravnica information is relevant. There will be ten mythic rare legends, which will likely be fun to build around and amazing, since they are now deliberately designing for the EDH crowd. Since it will be big set-big set, with five guilds (each guild is a combination of two colors) that means that each of those sets will have five of the shocklands.
A shockland is the shorthand term for the Ravnica duals such as Sacred Foundry, which has two land types and taps for those two colors of mana. It comes into play tapped unless you pay 2 life. These are super-handy in Commander decks, especially at three or five colors. There's one shockland for each two-color combination, for a total of ten. Five will be rares in Return to Ravnica, and five will be rares in the following set, named Gatecrash.
Before Modern was announced, you could get shocklands for $5-$10. I remember not wanting to buy some at a card show for $7. Now they are at the $20 range, give or take depending on the color combinations. Let me give you this financial tip ahead of time: KEEP THE SHOCKLANDS. They aren't totally necessary in two-color decks, but keep your lands, especially the green/X lands because cards like Wood Elves can go find them.
Finally, six cards from the upcoming From the Vaults: Realms were spoiled. The FTV series has been a fun one for EDH, because it's got new art, a different look to the foil and it's a reprint of some terribly awesome cards. When we know the whole list (we know that one of the cards will be from Return to Ravnica) I'll go over this in more detail, but the highlights for Commander are:
Dryad Arbor - I've never seen this played in EDH. Being a creature means it's extra vulnerable. Fun to play, but count it as a creature, not a land.
Forbidden Orchard - This is an awesome card for the three-to-five color decks. A 1/1 flyer probably isn't a big deal if you need the mana. I've seen some decks that combine this card with other effects to hurt creatureless decks. (Blasphemous Act & Repercussion, perhaps)
Glacial Chasm - Someone's going to drop this down and start feeling safe. Acidic Slime this thing away and teach them the folly of material things. This land is really no fun to hide behind, costing you a land, not tapping for mana, and requiring more and more life.
Grove of the Burnwillows - Again, there are decks that can abuse this effect (Kavu Predator comes to mind) and it's pretty easy color fixing. Run it and make some friends!
Murmuring Bosk - (new art) If you want to see what odd things Wizards can do when they push a tribe, look no further. This is a Forest that taps for three different colors of mana, so it's only good in five-color or the Doran colors (which is who this card was meant to enable). If you're in those colors, this is worth playing.
Urborg, Tomb of Yawgmoth - (new art) I'm excited about this, because I need a foil one of these for my Vampires deck and the foil is currently far more costly than I want to deal with. This is a classic combo with Cabal Coffers, works amazingly if you have Swampwalk creatures, and adds a layer of mana fixing to multicolor decks.
With six slots spoiled, and one from RtR coming, that leaves us eight more reprints. Here's my guesses: (keep in mind that I've been proven to be a terrible guesser)
Arcane Sanctum, Savage Lands, Seaside Citadel, Crumbling Necropolis, Jungle Shrine - This is the safest bet, to me. The Shards of Alara set was 2008, and these uncommons are up to a couple bucks each. They are elegant and supremely good in the colors that need them.
Riptide Laboratory - I think this is a good candidate because the supply is not what the community needs and it also has some Legacy applications. I have a couple of these and they are outstanding for re-using any Wizard, but especially for Venser, Shaper Savant.
Shivan Gorge - This is my guess for "sigh, really?" of the set. It is not powerful, but it is an effect you don't often see on lands. A great way to gain utility at a small cost. Runner-up: Keldon Necropolis
Wasteland - This seems to be what everyone is sure will be printed, and if it does, expect the sell price of the set to go through the roof. The FTV sets are marked at $34.99 but stores are allowed to sell them at higher. I've been told that they are an easy way for a store to make money. I as at a store after FTV:Legends came out, and they wanted $70. If Wasteland is in here, it will be the most-sought-after card, as it's currently at $50. It's got Legacy and Vintage appeal, and it's also an excellent EDH card, because nonbasic lands are often the most troublesome permanents to get rid of.
We are probably three weeks away from the fully spoiled list, so if you disagree about my speculation, I encourage you to comment below and tell me what will be there. This is a fun discussion to have, so fire away!