Two players who need to be looked at seriously are Beauden Barrett and Savea. The way they play disrupts the backline and the loose forward balance. If these 100-plus test automatic picks were judged as though they only had ten or twenty caps, would they even make the team? These sorts of players are also the guys who probably aren't going to change the way they play, whereas a less experienced player may be more willing to fall in line with a new strategy.
There also needs to be coaching accountability and the assistant coaches are going to find themselves in the firing line. I think the first replacement they'll be looking for is a defensive coach. That area is a mess. Others are in trouble too but they could see improvement by just keeping things simple and sticking to a basic, low-risk game plan, at least for the time being.
The other big question I have is how they come back from that defeat mentally. As a number of people have pointed out, the team looked like they completely gave up, which isn't something All Blacks teams do. Robertson fancies himself a motivator. He's got his work cut out for here but not just for the next game - they're going to have to step up mentally week to week.