Hit by Sauer was not quite late but the guy bashed his gloves into Kosty's face so it's no wonder he's dazed. That and his head hitting the glass but to me it's no worse than what Komi did to Thornton in the 04 playoffs with a faceplant into the boards for him. Looks like he hit his forehead or face on the ice on the way down, hence the bruising his face has already taken. At least he's conscious but day-amn! Looks like a facial injury/concussion indeed. Man, if komi did that with reffing of recent times it'd be 2, 5, 10 and a game! But I don't think it was illegal.
P.S. And now Kosty Jr. is showing some spunk. Way to go for the unbald Kosty!