I suspect the next step will be to go after the dealer who sold the gun to Dominick Black.
On August 25, 2020, Kyle Rittenhouse defended himself from numerous attackers with an AR15 type (Smith & Wesson M&P 15) rifle. The rifle was not legally owned by Kyle. He had legal possession of it. This was due to a quirk in the law. People under the age of 18 have always been able to buy rifles from private owners and possess them, but they are not allowed to buy them from licensed federal dealers.
This correspondent noted the dropping or dismissing of the Wisconsin weapons charges against Dominick Black, was almost certain, because the Wisconsin weapons charges against Kyle Rittenhouse were dismissed by Judge Bruce Schroeder during his trial.
A prediction: the charges against Dominick Black will be dropped or dismissed.
The dismissal is likely to occur on 10 January, 2022.