the difficulty scales so that players should be either at or near level 60 (max level) at the end of hell difficulty, leaving inferno with a flat difficulty curve throughout.. this means act1 inferno will be equivalent in difficulty to act 4 inferno. due to this, and since there won't be any "run" business needed to max out your character level, "the grind" is gone. it's a very simple way to get people to play through the game again rather than grind down certain convenient high-exp areas. MF has been changed also; act bosses or superuniques won't have any better drops than random champion packs scattered throughout the game. with that change to MF, there won't be any specific advantage in terms of experience or item drops from running a particular boss over and over. will certain players gravitate towards only replaying certain portions of the game? sure, but there is literally no upside to doing so. to the contrary, the nephalem valor buff will make it more productive in terms of the outcomes of "grinding" to continue playing through a single game as opposed to running a particular area. that buff gives a bonus to MF when you kill a rare/champion monster which stays on your character as long as you stay in the game and do not change any skill/rune choices. "the grind" is now "playing the game." the old grind of countless baal/meph/whatever runs for either xp or loot are gone.