I don't see any particular issue with giving Shaw another chance next year. Lest we forget, he's a 2.7 overall bWAR player this year -- that's not only not bad, it's bloody above average. The package is good here. Not mediocre, not OK, not "Yes, however." GOOD. Yeah, he teased us with that super streak he went on in the early months, and then settled to earth a bit, but the overall package is still very satisfactory for a third baseman.
Let's not forget Shaw was not a big offensive prospect out of the minors, our expectations in April and May before the league had really seen him were simply too high. Just because a guy doesn't hit like an All-Star doesn't mean he's useless. In fact he's almost exactly where I predicted and expected he would be at the end of the season. And I do think Shaw will hit better in the future with more big league experience under his belt. He's going to be on the roster regardless, either starting or benching, so in the absence of any other incumbent worth naming (Flablo is definitely not the established incumbent at this time) there is no real reason not to give him a chance.