I've got my eldrazi deck, and I've been thinking for a long time what it takes to beat it.
In affinity Painter's Servant shuts it down. Could also run Shrapnel Blast.
In control they need to run Spell Snare, Forked Bolt, Roast.
In burn Lightning Axe and Flame Slash.
That all in red deck is a hilarious matchup.
Death and Taxes is a hilarious matchup.
Some kind of Boom/Bust dark dwellers control deck probably shafts eldrazi hard.
There are ways to deal with eldrazi, but I'm not sure I trust people to figure it out. I would anticipate actual silver bullets for it in Shadows. In the end, if eldrazi is to stay, some new card probably needs to offset it (wasteland?). Otherwise Eye eats a ban, and even then I think that only gets rid of aggro variants.