Kevin Costner Says 'Yellowstone' Comeback Possible Under Right Circumstances

Kevin Costner says the door is still open for him to gallop his way back into his lead role in "Yellowstone" -- but with some conditions ... including having a plot that's ready to shoot.

The actor made it clear on "TODAY" Monday that he loved his hit show from day one, and still does ... so he'd definitely re-open the window for Paramount's Western epic -- but he notes ... without scripts all ready to go, it might be difficult to do that.

Kevin says script delays pissed him off to the point that he felt he needed to leave the show -- noting they lost a full year without anything to show for it ... and that's a no-no for him.

He also says he wants to be able to do other things instead of just shooting "Yellowstone" -- a la the Western epic film he's releasing this year -- but he finishes by saying a possible "Yellowstone" return is still in the stars ... assuming they can get on the same page.

While there've been countless reports and rumblings of issues on set between Kevin and creator/showrunner Taylor Sheridan -- Kevin makes it seem like things aren't so bad.

When Savannah Guthrie jokingly says it sounds like he's saying there's a chance for him to come back to the series -- Kevin says that's exactly right ... pointing out that everybody loves the show, and that "Yellowstone" probably deserves a proper ending.

In the meantime ... KC is focusing on plugging "Horizon: An American Saga" -- which is also in the cowboy vein, albeit in a film format. It's being split up into two different releases.