Sigh, this topic is a dead horse imo.
Not having Bind or Sleep hasn't been that big of a deal when I've been tanking as we still can open with Weapon Bash and Last Resort, then Stun, Aspir, Enfeebs, Stun, Aspir, Enfeebs, repeat until capped. If the elemental increase is significant, then what jprvoices said in the Ninja Updates thread will play a significant role in how we tank. Also keep in mind we have no idea what the two new Ninjutsu are nor do we know how much enmity they will generate.
That said, I think NIN/BLU is going to be a viable tank, but it's not going to be on par /DRK until 96 when the last of the hate spells (Jettatura) is available because Weapon Bash and Last Resort are that good for initial hate (plus Absorb-TP will be available for /DRK at that point too).
At the end of the day, things are changing. If folks choose to resist modifying how they play the job, that's on them, those who are willing to expirement and adjust will thrive, because everything we need is already there, we just have to learn how to take advantage of it.
To answer your question about Enchu, the answer is no, the katana is Rare and thus we can only use one, kind of a bummer, but that's how it goes.