Who's leaving ER spoiler

Ok I just read that Luka is leaving at the end of this season and possibly making a few special apperances next year and also Kerry is supposed to be leaving and going to Florida in the show. The two that hold it all together in my opinion. I am curious how the show will hold up after this season if they both do leave. Goran seemed pretty confident. Like it is already decided. So I haven't heard much of Laura. If anyone knows details please tell me.