If you read the article you will see that in Diablo II enemies only went up to lvl 85 but players could be up to lvl 99. In Diablo III Inferno difficulty will have monsters lvl 61 and up while players can only get to lvl 60.
So no matter what even the easiest monsters will be higher level than you in inferno difficulty. It should be very hard.
part of what made d2 hell so difficult was not the monster levels but the increased number of modifiers on them... stuff like immunities, faster attack speed, faster movement speed. they could easily tone this down for d3 hell and put them in inferno.
just saying it's entirely possible that this will be the case. i hope not though.