Indeed, it sounds like Titanfall as a debut game will remain a Microsoft-platform exclusive, but the future of the franchise -- once Respawn is no longer a "startup" -- may make its way to PS4. The studio head added, "Of course we will [make PlayStation 4 games], just not the first Titanfall."
Always MS exclusive at launch, great partner and focus is good for a startup. EA made a deal for the rest, we only found out recently.
http://uk.ign.com/articles/2013/10/29/titanfall-an-xbox-one-360-pc-exclusive-for-its-lifetime