I didn't have any trouble getting my wizard (Squiggles) to 17th with no familiar. I'd imagine you could probably do it with a Sorc as well (you just have to be EXTRA careful about spell choices rather than really careful!). Just buy a crossbow and shoot stuff while your summon chews on it...
Druids have still have their summons and Animal Empathy works as well. I think Ancient Dire Bears got made uncharmable but regular Dire Bears are probably still a viable option.
So yeah I wouldn't say no to a level 17 Panther pet with uber sneak attacks

but by the same token you can survive quite well without one. You just have to be crafty!