The answer is - there are no guarantees to a team or a conference that they will be in the CFP. The way to get in is be ranked in the top 4 of the CFP poll.
And in a year where the Rose/Sugar are the semi-final games all a team has to do to be guaranteed to be picked as an at-large is be in the top 3-5 highest ranked teams below the contracted guarantees...
A peak at who would be in and why based on this weeks poll...it is conceivable that an undefeated BYU could be in the top 10...
http://www.cougarboard.com/board/message.html?id=13341801
Here is much more information on CFP/NY6 if you want to read more (like for example that they couldn't by pass a #5-8 ranked BYU for another at-large that is lower ranked regardless if they think another team will rent more hotel rooms or buy more tickets or beer)...
http://www.cougarboard.com/board/message.html?id=12810785
It is all about whether we are ranked that high in the eyes of the CFP committee members and what ever calculations, film or polls they may review to make their decision...