In early levels (heroic tier) you should be able to hit with a 10, easier in some specials conditions like flank, attack boosts or defense penalties, wich makes you, in most of the combat, hit with a regular 7-8.
Our rogue had 12 to-hit with at-will powers at level 3, in some encounters he could hit even with a 2-3 rolled in the dice against same-level monsters.
But each class can deal with the progression in different ways, fighters and most strikers can always pick feats to boost "hit" and boost primary stats. Some other players may have dificulties with this progression, like multiclasses, that demands a lot of feats and you may have to split some stats points.