i think his strategy is pretty obvious at this point. he's using minor crimes, sometimes unrelated crimes, to force compliance with the investigation while looking up the chain.
kushner and juniors business dealings for the last 20 years are ripe for unpardonable, jail sentence magnitude crimes, and with that leverage, he has/will gain access to trump himself.
anyone doubting mueller's wide jurisdiction needs to remember that is how we went from shady real estate deals in Arkansas to lying about a blow job being impeachable in the 1990s. everything really is fair game. and if lying about a BJ is impeachable, trump is done the second he opens his mouth under oath.