It's possible they could print more cards with "~ enters the battlefield tapped" and "When ~ enters the battlefield, you gain 1 life". But it's also possible they could print enemy-colored counterparts to the Cloudcrest Lake cycle in Kamigawa. In the case of EC Refuges, maybe if they return to Zendikar. Or they could reserve such cards for a future block much like the duals in Innistrad, which for some reason compliment the Glacial Fortress cycle in the core sets.
Don't get me wrong, this excites me greatly, but the Eldrazi seem undefeatable... Would the return be about the denizens of the plane trying and losing?
Why not? The multiverse has survived for eons with the Eldrazi swimming in the Blind Eternities, surely it won't be that much of a problem. Or maybe the Eldrazi suck all the life and mana out of Zendikar, but remain mode-locked in their physical forms and die of hunger.
And the Eldrazi have already been defeated. The chance of them being defeated again is pretty small, but not zero.
"What is etherium but the next logical step?" It's all my fault.Show
Not to mention when don't have a sense of time passing. The Mirrians lasted long enough for Koth to find other planeswalkers to help fight Phyrexia. Sure, they ultimately failed since Phyrexia already had control of the plane at that point, but that's beside the point.
I see no reason why the various peoples of Zendikar couldn't hold out long enough for Gideon to find some back up. Not to mention since Bolas is still out there, I don't think he'd take well to not being the big bad of the Blind Eternities.
No enemy is every truely undefeatable. Things don't look good of the denzins of Zendikar, but they could still pull through some how.
Eldrazi have great power but don't seem to be very intelligent to me. They're just ridiculous strong beast-god-things, aren't they? Unlike phyrexian armies they're not interested in conquering the plane as fast as possible, they just want to statisfy their ceaseless hunger. More instinct-based than conscious. This makes them predictable and (up to a certain extent) controllable. Yes they're literally annihilating everything in their path but it sure will take a while for them to completly devour Zendikar.