It will likely take a while for a newcomer/returnee to be able to play extensively in the newest expansions, if they are not strongly supported by guild or friends. The game in general is more oriented towards group play, content-wise. However, a number of toons could go and kill a few trash mobs in new Overthere, at lvl 105 with autogrant, with level appropriate group gear and a merc. Not sure that it would be as fun as to find a group to play with.
