Not long ago, it was announced that Inferno difficulty was going to scale with increasing difficulty, as opposed to being linear. Previously, Blizzard had planned to keep all of the mobs mlvl (monster level) 61. Now they’re saying that only Act I Inferno is going to have mlvl 61 mobs, with the subsequent acts containing more formidable demons and beasts – all the way up to possibly mlvl 65 at the end of Act IV.
At the time of release, all of the end-game gear will be available – starting with Act IV Hell. Conceivably, a player could farm act IV Hell, over and over, and eventually gather up all of their desired gear. However, players who start playing through Inferno will enjoy an increased likelihood of getting the stuff they want – especially in Act IV Inferno.
Quote from Bashiok
Item pools are not limited by Act, or Boss, or anything like that. While you’ll have a better chance to get better items in Act IV Inferno, you could get those same items in Act I, or even Hell. (Source)
Inferno difficulty is unlocked once a player has completed the game on Hell difficulty. Players completing the game on Hell will already be level 60 – which is the level cap – which means that Inferno will likely only cater to the more serious players who are interested in achievements and bragging rights. The casuals will likely start a new character once they’ve finished Hell on a particular class.
To give you an idea of how challenging Inferno is going to be…In Diablo 2, players could reach a level cap of 99, yet the maximum mlvl in Hell was only 85. In Diablo 3, players are capped at level 60, with monsters in Inferno being mlvl 61-65. Comparatively speaking, finishing Diablo 3 Inferno would be akin to beating a level 109 Baal. Tell me that wouldn’t be brutal..!
Blizzard is claiming that even for the very best players, Inferno will require months to complete. That sounds promising. If it’s truly that difficult, it should keep players engaged for quite some time.