Since we are essentially just guessing what they will do here, my guess is they will just start with cease and desist letters to the dispensaries. They will have some grace period to shut down. The raids and seizures will be against the grow ops.
Their typical MO is one of shock and awe; essentially terrorism - fear and intimidation. They can get a LOT of tv and print coverage as they chop down thousands of plants and seize tons of product. At the same time, they will seize property and bank accounts. And of course, they will conflate all of this with cartels and diversion of product to the black market.
Then they will move against the dispensaries.
None of this will take thousands of people; a few dozen case workers and small teams of field agents would do it. They will surely find guns and other drugs at some of the locations, which they will tout as evidence that not all is peaceful or just "a legal business".
You can almost sit back and write their script.