Just remember that if you give the new difficulty the best items then you're making it mandatory. There's no way around that.
It's something to keep in mind.
This is so true. It has to feel "just right".
Keep in mind, first...the idea of what the "best" items are will be changing with Loot 2.0...and Paragon 2.0 as well.
Currently, "best" refers simply to items with the highest stats, and the tightest bundle of the following: Crit Chance, Crit Damage, Main Stat, Attack Speed, Vitality, %Life, All Res...maybe Armor. With Loot 2.0, a legendary that drops that doesn't have one or more of those things can still be amazing based solely on the extra aspect(s) it has, that adjust a player's skills to work way better. And with Paragon 2.0, if an item drops that doesn't have one or more of the above mentioned stats, Paragon Points can be spec'ed in such a way to make up the difference. Meaning, in addition to making a wider range of items "good," there may even be a slightly higher demand for either class-specific rares with skill changing aspects, or general rares with skill changing aspects.
Thus, the "best" items for one person may not be the "best" items for another. Obviously, sure, some items will likely be incredible for most players' characters...but for the most part, Loot 2.0 and Paragon 2.0 not only seek to improve item and character quality, they'll allow players to place their own value on items, and not so much "everyone wants X, Y and Z."
That being said...you guys are correct, in a way. I was honestly just riffing off an idea on where to put different levels of items. Like I told Miles, specifics would definitely need to be worked out in that area. However, I understand the concept...wherever the most potent items are, that's where people want to go to farm and battle, in hopes of acquiring those great items. Then again, I think that can be slightly mitigated by exact difficulty, though.
If Torment were to be added to the very end (i.e., made harder than Inferno MP10), and maybe only a scant few special high end (perhaps BOA items) drop there, how "mandatory" can it really be if a vast majority of folks can't farm there? Mandatory means "farm here, and you can get the items that allow you to handle the entire game." Mandatory isn't, "this area is ridiculously too hard, and you can still handle the rest of the game even if you never go here."