No way Randy and GBox would ignore the PC. It's possible that it might be console-first with a PC release some months out (hopefully not GTA-like gap in release), and if that means better optimizations for performance and menus on a PC, then I'm fine with that (lol--like that will ever happen).
...I wonder what a "true open world" means for an FPS like Borderlands? hundreds of useless POIs to cram content, constantly respawning mobs that merge into other mobs and create obnoxious farming issues? I guess it would mean adjustments to loot drop rates and farming, because you couldn't really map in and out to reset mobs (other than reloading the game, which is terrible).
...or is "true open world" a mere euphemism for the yet-to-be-announced news that this will be an MMO? I hope not... (There was plenty of speculation with BL2 that the new sequel would go that route, based on the way BL2 main story wraps up. The brief "present time" story sequences in TPS suggest that as well)