Plastic armour kits mean the most common complaint I've seen about playing Horus Heresy (buying expensive models and then having loads of parts left over when you buy the Legion upgrade sets) isn't going to be as contentious an issue.
I don't think anything serious about "tiers" of the game is every likely to occur, they want people to play all their games and be able to buy as many models as they want, they won't want to restrict people and they don't want to stop parents buying them a massive expensive Horus Hersey box for Christmas!
People have been talking about the tiers of play idea for ages and its just never panned out that way at all.