I also thinks they will still add stats to the daggers for two reasons:
1. It costs 10k gold. You'd expect to get something in return for that.
2. Why would you have epic quality daggers of ilvl 397 if they are worse than T12 normal (this is a guess, haven't simcrafted it) Why have something you can equip, but cannot really use?
and actually you can add a third consideration:
3. Why would there be no stats on this, but the caster legendary has?