I think the 4 mana 1/1 taunt would potentially be playable in handlock. It's at least in competition, because it can do things like get the stats of the molten giant you just played for free and have taunt. It depends on what else out there is viable due to changes in classic cards. It's a card that is good enough to be run, but you can't really know if it's good enough to make the cut until you know what the card pool actually is. I mean you only even need to get 3/5 worth of stats for it to be the same a Sen'jin, and I don't think it will be that hard to get better than that.
I also think the N'zoth or whatever it's name was is playable in Paladin for sure, and quite possibly Priest. Yes it's slow, but that shit just wins games. You get two big bombs with it like Tirion and Sylvanas, game is over. Sure it is slow, but in control decks you have to plan on going through most of the deck anyways.