re: So is it official that P5 teams will now only play each other?

I don't think it is anywhere near happening. It sounds like one of those things people would be in favor of but it won't happen IMO because the lower tier P5 schools will continue to worry about financial issues (e.g. enough gates from home revenue).

If all of the P5 schools actually played two P5 schools ooc every year that would be a major victory and great for college football. I think the playing P5 only or only playing 1a schools is a silly and ineffective policy to endorse.