We the readers never find out what happens to Wilson's garage after he kills Gatsby. Before this, however, Wilson told Tom that he and Myrtle were moving. Wilson decided to make this move after he found out that Tom and Myrtle were having an affair. Of course, when he told Tom this information, Tom just sounded surprised.

Since this novel takes place during the Roaring Twenties, one might assume that the garage is put up for auction and sold. We can assume so because George probably went to jail after he shot and killed Gatsby. Other than making a prediction, we never are told what exactly happens to him or his business.

In Fitzgerald's novel, The Great Gatsby, George Wilson runs a garage in the "valley of ashes" between the Eggs (West and East) and New York City. Wilson is described as somewhat lifeless and frazzled. In chapter seven it is revealed that he has discovered his wife has been unfaithful to him. She has actually been having an affair with Tom Buchanan, who knows Wilson and sometimes does business with him.

When Tom, Nick, and Jordan stop at the garage on their way to the city, Wilson tells Tom he is planning to leave and take his wife west. He inquires about a car Tom has agreed to sell to him. Wilson hopes to make some money on the car so he can leave as soon as possible. Wilson never reveals what he plans to do with the garage. Presumably, after he kills Gatsby, the garage will be taken over by someone else.

For further discussion about the symbolism of the garage, see the link below.