I think there is a real possibility that Irving is the only Celtic that makes the all star team. I think Hayward is going to be brought along very slowly and the rest of the team is going to take stats from each other, such that there will be players with far better stats (many on good teams) that are more likely to make the team (that said I would project Irving and Horford with Hayward as an outside shot if he is healthier faster than I anticipate right now).
Guaranteed barring injury - Irving, Giannis, Embiid, DeRozan, Wall, Oladipo
Likely barring injury - Simmons, Porzingis, Love, Griffin
Fighting for last 2 spots - Hayward, Horford, Tatum, Beal, Lowry, Drummond, Dragic, Middleton, Walker
There is always someone that comes out of nowhere as well, like Oladipo last year. Maybe IT has a huge season, for example. Maybe a rookie really impresses and just blitzes the stats.