Azhdar: Hope it will be Bloodlines 2. :)
hyperagathon: To recapitulate: Obsidian and Paradox have gotten very chummy, the recent trademark filing, Boyarsky rejoins Cain, they'd probably use Unity for a Arcanum or ToEE sequel while Unreal is mostly used for 3D...I think it's a reasonable assumption, but we'll see.
Well for it to really be the "Troika" you'd need all three, I don't know if Jason Anderson is even still in the games industry though.
Regarding PoE2 a sequel could be good, probably would be better in a completely different part of Eora (Arabian-like desert land, seeing as they already used "temperate medieval land" in the base game and "snowy viking north" in the expansion.
Mechanically there's some new things that weren't included in PoE, multi-classing, familiars and summon-able creatures, a more expansive skill system (better than just the 5 or so in the original). Oh and an XP skill that actually rewards you for winning battles :/