It's pretty much spot on with the one used in Master Chief Collection, except that game confuses the issue by having an XP system alongside it.

In MCC, you get a weekly set of PvE and PvP challenges (as well as seasonal) that reward you with unlock points for the "Battle Pass". This is the only way to unlock cosmetics outside of a few challenges tied specifically to unlocks.

There are also challenges that only give XP, as well as XP gained from playing matches. However, XP ONLY increases your rank, which is an emblem next to your name. Nothing else comes from it.

It sounds like Infinite is getting rid of the useless parallel system and combining it into one, while removing the match XP (which again, didn't really do anything).