A Sinister Six line-up could be doable, especially if (Spider-Man Far From Home spoilers)
They've already introduced the Vulture, the Shocker, Scorpion, Mysterio, and kind-of-sort-of the Chameleon (at least, I'm assuming that's who Dimitri from Far From Home was meant to be). Throw in Doc Ock, and it's a decent line-up, though they'd probably need to take a movie to turn Scorpion into an actual super-villain rather than just a criminal. (though I'm not sure how well the Vulture would work together with the others, or if Dimitri was picked as a generic Russian-sounding name as opposed to being a reference to the Chameleon - SHIELD's already introduced technology in the MCU that it seems like the Chameleon would use)