I do not think he will turnaround against Nadal BUT him playing hard and winning even he is not playing well is an encouraging sign. At the very least, he is showing that he does indeed like tennis even with all the distractions going around him off the court.
In my opinion, after the US Open, he should just shut down his season so he could mentally reset. Watching him play right now he is just mentally struggling right now. Playing more tennis (at least after this US Open) will not help him mentally.