Basically, if the CFP expands, they are unlikely to guarantee a spot to anyone, but, in the event that they do, they would only guarantee a spot to the highest ranked G5 champ. In the case of a guaranteed G5 champ bid, that would serve as the defacto only opportunity for the G5 to make the CFP regardless of how many zero or 1 loss teams come out of the G5 (i.e. similar to how the current format excludes UCF, and the current format would likely continue to exclude UCF even if it defeated 4 P5s OOC in the regular season that included a P5 champ*).
*Look at this season. 13-0 Alabama, 13-0 Clemson, 12-0 Notre Dame, 12-1 Oklahoma, 11-2 Georgia, 12-1 Ohio State, 10-2 Michigan and 10-3 Washington**. Even if UCF's 13-0 included a win over any of those teams (other than already multiple loss Georgia, Washington and Michigan), the ACC champ game loser (which they did beat this season), UNC (which they had on schedule this season but got cancelled), and fill-in-the-blank ranked but non-NY6 P5 - say Washington State, does anyone believe that they would actually get in to the exclusion of 5 of those teams?
**It was easy to rank UCF above Washington this season because it didn't matter - UCF was going to the access bowl regardless and Washington was going to the Rose Bowl regardless. It's similar to how it doesn't matter that Georgia was ranked above Ohio State - Georgia was going to the Sugar Bowl regardless and Ohio State was going to the Rose Bowl regardless. However, the outcome could have easily been different if the exact ranking mattered.