Whether he actually gets charged deepens on two things. Exactly what is in the boxes and what was his intent? For example, if these classified documents should have been declassified years ago because secrecy is not needed and these documents were packed by mistake, then there was no intent to break the law then there should be no charges or just a misdemeanor.
On the other hand, if the defense of United States would be seriously compromised if these documents fell into the wrong hands and Trump intended to take them, then he should charged with a felony. This seems most likely at this point in time.
Although from a legal stand point, the AG should not be concerned with the repercussion of charges, he will certainly consider it. We just had an FBI office attacked by a Trump supporter with deadly intent. Threats of civil war, and violence against the government and government officials is all over social media. The claim that the election was rigged resulted in an attack on the Capital. What actions might we expect from these people if their beloved leader were jailed.