i really really really hope there will be no ladder reset ever! with all the random stats and the RMAH it seems pretty impossible to do so. also, ladder resets worked so well in D2 LoD because you could build a good gear setup with relatively cheap runes from scratch
I think a ladder system would motivate the more regular players to play more and motivate themselfs to farm better gear. Something that happened to me by finding a youtube video of a uber demon hunter motivated me to start playing again.
I hope the time it takes to develop PvP will deliver awesome game modes. Some kind of battle grounds or objective based games besides normal arena. Anyway I will be happy for PvP regardless the quality.
As much as some people have been waiting for PVP, I think the game has lost too much of its player base at this point for it to make too much of an impact. Don't get me wrong, I still love the game, but there would have to be a dramatic overhaul to draw back the crowd I'm assuming Blizzard is expecting.