1) Every individual will be saved;
2) Christ's propitiation was insufficient to save ANYONE and needs to be "completed" by our faith - this makes us atone for our unbelief by believing and is a very subtle and dangerous form of salvation partly by Christ's death and partly by our faith (and repentance, of course, because that is how we stay saved after we are first saved, because Christ's death only dealt with PAST sins! Er, weren't they ALL future when Christ died.....???).
Another interpretation of I Jn 2:2 is that Christ is not only the propitiation of the sins of John and his readers but of people from every nation, tribe, tongue and people (a perfectly possible meaning for cosmos, as I'm sure you know - the same meaning that can be ascribed to Jn 3:16).