Level cap isn't all that, there are some legendary armour that I prefer to raid gear because of the perks. Honestly, I like some of my gear that only gets me to 27. In fact I prefer it. So no, those new items won't be useless. Level cap it's only to help you with the raid, be on a more even field. In regular crucible, I'd rather be a 26/27 with some sweet perked armour. Consider that?