Yes, they will be a force in the playoffs. Losing Gallinari was not ideal, but this is about the only team that could lose one of its "stars" and have it make little impact. They actually have a greater net rating with Brewer, Chandler, and Iguodala on the floor without Gallinari than when he plays (and their defense greatly improves - almost 7 ppp, as he is a liability in that area). Their depth is tremendous.
They have been playing without Lawson now for awhile too. I have been continually impressed with this team and their growth over the season, and although I don't think he will get it because of obvious other contenders, I think Karl deserves serious consideration for coach of the year.