I've only just been getting into the lore a bit, and Phyrexia is probably my favorite "concept" in MtG, along with the Eldrazi. I'm not a big fantasy buff, but love sci-fi, and both seem almost more sci-fi than fantasy. In any case, don't the Phyrexians sort of need a plane with an established mechanical infrastructure? If so, I'm wondering whether or not somewhere like Kaladesh might make sense as a target?
Also, what ever happened to all the Mirrans living in the Forge? Is it not possible that the next set involving the Phyrexians involves a civil war between the various factions, with the Mirrans and Urabrask doing their own thing? And I'm not being rhetorical, is there some lore reason this wouldn't be possible?