The murloc will probably just give 2 attack to all the other murlocs. With that cost and stats, it must have a very good text like that.
-----------------
Actually they can't change backstab really. Making it 1 mana it will be worse than other basic cards like holy smite, living roots or arcane shot.
They can't change its text either really, a zero mana deal 1 damage to an undamaged minion? That's worse than moonfire. So I think that's set.
-Fan is too good. As long as you have fan, you don't play a perfectly good card like Dark Iron Skulker because fan is more flexible, it draws you a card, you can cast it for 0, it scales with spellpower and so on. I think that's a card that should change to like 4 mana. It's balanced then, you draw a card for 2 mana and an arcane explosion for 2 mana in one card. Board clears are probably going to be very strong in the new meta, it's still playable.
-Sap is the other basic card that's too good. If they are concerned about silence, they should be concerned about this. I don't think the effect will change but it should cost more. Compared with entomb it's balanced but they kind messed up with that card too, it's under costed. A 3 mana sap is still good but you might not want to play 2 maybe.
The other auto include basic card is deadly poison, nothing is wrong with.
More problematic cards are actually non basic cards. Shadowstep for one, 0 mana cards are just too good in general, shadow step has enabled stupid things in the past, can do again in future. It's not played now but, say you can shadowstep your C'Thun and it apparently keeps the buffs! That' s a pretty big problem there...
Prep will forever limit the design of rogue spells, I'm surprised that's not on their radar but then they are not touching innervate either, so I guess they find it to be a core card to the class, which it is.