U will be able to craft any C/U/R/E rune, but it'll be much more cost effective to trade. Say to make one exo u need to shard 3-4, so trading 2 u don't need for 1 u do is still very viable. Think of sharding just setting max and min prices of runes, so there is never unobtainable stuff. All limiteds will their legendary versions available as random 11th rune in packs. Limited versions of existing runes will remain limited. They will be rare drop tho.