Speculation that Trump would pardon Manafort and Gates is probably irrelevant. Manafort and Gates’s alleged federal crimes almost certainly could not have happened without committing state crimes. State attorneys general could build cases off of Mueller’s investigation and effectively neuter Trump’s power. A president can only pardon federal crimes.
Amendment XThe powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the states respectively, or to the people.