I think LSU's ranking is the cut off line. In the CFP's "mind" there are only 7 teams in consideration right now. I'm not saying WSU or OSU can't rise above that threshold, but I don't think the committee is running scenarios that include Washington State or Ohio State.
I think LSU is the cut off line in the sense that if you aren't ahead of LSU when the dust settles then you aren't in the conversation. However, there are a lot of games left to be played and the three teams currently immediately behind LSU (WSU, WVU, tOSU) all will have opportunities to prove that they should be higher (or not) while LSU doesn't really have much left in terms of opportunities to move up.
West Virginia, Ohio State and, to a lesser extent, Washington State have a much better chance to improve their situation. LSU's only remaining games are against a cream-puff Rice team and a barely over .500 aTm.
West Virginia has .500 OkSU, #6 Oklahoma, and (if they win that and possibly even if not) the B12CG against #6 OU, #15 TX, or #16 ISU.
The Buckeyes have .500 Maryland, #4 Michigan, and (if they win those) #22 Northwestern.
Washington State's situation is not as good as Ohio State's and West Virginia's because the Cougars can't knock out anyone ahead of them but their last three games will be .500 Zona, #18 Washington, and the winner of the messy Pac-S race between #19 Utah, ASU, and Zona. One thing that helps the Cougars is that the PAC-S winner is likely to be a team that wins their last two regular season games and finishes ranked.