Quote Originally Posted by ESG View Post
If fetchlands were gone, people would max out on dual lands to ensure consistency. A deck like Jund would go from playing 5 or 6 duals to playing 12. This would put a lot more pressure on prices, which would be a large negative consequence. I honestly don't think Legacy would survive if duals saw, say, a 300 percent increase in price. Shops would have to start allowing some number of proxies, and the format would go the way of Vintage.
This part is definitely true. It would probably drive most Legacy players into Modern, though since a lot of the secondary market (SCG most prominently) is heavily invested in Legacy, it might increase the odds of Wizards printing some better-than-Ravnica-Duals (but not reprinting Alpha Duals) in a Conspiracy or Commander product to keep the format going.

From a gameplay standpoint, City of Brass and Mana Confluence would see more play. Stifle would be a lot worse. Traditional land destruction would get considerably better because people couldn't just sit on uncracked fetches, and it would be easier to color-screw someone. Because of this, four-color decks like Deathblade would basically be wiped out, and three-color decks would lean on things like Mox Diamond and rainbow lands. Deathrite Shaman would be significantly weakened but would still see play in Elves (as a utility card rather than initial acceleration). I could also see Elves going back to Crop Rotations in order to turn on Shamans. People might play some number of Mirage fetchlands; it depends on how fast the format was and how significant the presence of Wasteland was. I could see Miracles running some number of those. Blood Moon would get better because people couldn't just play one or two basic lands in their deck and expect to see them with any regularity. Mono-colored decks would improve due to having consistency advantages over the three-colored decks. Combo decks would probably get better, relative to the field, because Brainstorm decks would be weakened. There would be much less digging and flexibility. Mulliganing would be more or less what you got. Another possibility is that the Brainstorm decks would increase the number of cantrips, especially Ponder, in order to still have superior library manipulation.
I agree with you (and with Julian) that monocolored and two-color decks would get a lot more popular for both availability and consistency reasons, but I'd go so far as to say that three color decks would become exceedingly rare as once you were committed to three colors it would make little sense not to go all the way up to four or five and get whatever cards you need or want since you're running City of Brass, Mana Confluence, and exposing yourself to nonbasic land hate already. I could easily see a 4 or 5 color control deck being strong in such a format. An old school Miracle Gro deck running Land Grant might spring up, but Tempo as we know it would be dead. Blood Moon be relegated to sideboards in the medium to long run because the relative popularity of basic land-heavy decks would mean that it wouldn't be nearly as maindeckable as it is now, though it would be an absolute blowout against the 4 and 5 color decks. Raw card advantage like Night's Whisper, Ancestral Vision, and the new Khans Delve draw 3 spell would get better.