Gus' laundry (or at the least the superlab beneath it) burned to the ground in the season 4 finale. Additionally it's well known to the cops after these events so there is nothing to do there. School.. he's been fired (or suspended) from it after he made a pass at the principal which could have been constructed as sexual harrassment. Car Wash.. well, it's a money laundry front and that could hurt Walt in the short run but they could always find another way to build up a front if everything blows over and they win. Another possibility to get Walt good is to take Saul out of the equation. Saul has tons of contacts in the shady, criminal underworld and has bailed out Walt many times out of tough situations. However Saul is cunning and probably has covered all his tracks and knows the system inside out. Getting him would be very difficult. So i stand by my statement.. Walt's family is his real weak spot. Skylar not so much (maybe Jesse knows she's complicit or he at least suspects it) but Jr. only knows the official version as much as he dislikes it. We'll see soon enough.