If you haven't watched Daredevil yet, first of all, shame on you. Second of all, the spoiler below isn't huge, but you may not want to read it.
With the Kingpin jailed at the beginning of this next season of Daredevil, and with the upcoming Defenders and re-rebooted Spider-man coming to the MCU, I can only imagine the many villains to grace us in his stead, or partnering with him in order to take over New York City.
My guess is that Hammerhead isn't far behind. Let's look at some of his history and then submit your votes for casting.
As a young boy, Joseph and his family fled the Soviet Union with the help of a man known as The General... Hammerhead began his career as a junior hit-man, working for the Maggia. When his head was shattered in a brawl, Jonas Harrow discovered him in an alley, and operated on him - replacing his broken skull with one made of steel. Hammerhead clearly had mental and emotional problems prior to his injury, and they were exacerbated by the trauma. Upon awakening, Hammerhead became fixated on a 1920's movie poster which had been the last thing he saw before the brawl. He adopted the identity of the mobster "Hammerhead", favoring 20's clothing, weaponry, speech patterns and behavior of the criminals of that time. He claimed to no longer remember his real name. Hammerhead was involved in a major gang war after Wilson Fisk decided to lay low - leaving the way open for Doctor Octopus and Hammerhead to lay their claims as his replacement (marvel.wikia.com).
I also found this piece particularly telling for his eventual rise to the MCU:
During the events of the Civil War, Hammerhead used the vacuum left by the incarceration of the Kingpin to gain a greater foothold in the ranks of organized crime, attempting to organize an army of costumed villains (marvel.wikia.com).
I predicted something like this might happen a while back, but I digress... to the polls! Vote for your favorite actor to play Hammerhead below. I've got some big names, small names, perfect fits, and some for variety, so be sure to have fun with this! Maybe Marvel exec's are watching us right now.