I'm sure LucasArts will try and have a KOTOR:3 made. However, LucasArts bombed with Gladius. They canceled Sam and Max 2. Several of their titles have really bombed over the past few years.
(Super Bom-Bad Racing, Episode 1, Rouge Squadron III, Racer's Revenge, Clone Wars, Bounty Hunter, etc. etc.)
I don't think Jedi Academy did very well.
It's possible that they don't have money. I'm sure LucasBooks, LucasFilm and the like has money. But why pump money into a division that isn't turning a profit?
If Battlefront, KOTOR:2 and Republic Commando sell well, KOTOR:3 is far more likely to happen.
It's also possible that Obsidian doesn't have the full staff to do NWN:2 and KOTOR:3 at the same time. LucasArts may shop around for another house, or see if Obsidian can hire on another 20 staff-members.