Some people believe Priest got buffed because the crying masses clamoured their disastifaction on public forums. I sure hope Blizzard has better metrics to gauge Hearthstone class balance them just online complains.
Still, when one class is in the dumpster people cry, and when the class get eventually buffed some people believe it was by the power of their tears alone.
I think a game like Hearthstone will always have a top and a bottom class and honestly, I am more concerned about one specific class being utterly dominant than one being trash. 1 trash class means I still have 8 match-ups but if one class dominate this means half of my games are against the same class, sometimes the same deck.
I expect Priest to be better on the next expansion. I don't know if it will be top but they may have a chance. Rogue though, I don't see they making it.
Perhaps on the next expansion? Start comboing those tears boys!