It is unlikely that Punisher will debut in Agents of SHIELD.
1. The series' aesthetic is not compatible with the bloody, mature content of the Punisher tales. First, the program is a Disney program airing on ABC, a family oriented channel. It is unlikely that Disney would approve such content, as it would alienate the viewers. ABC is not NBC. Secondly, the series' lifeblood is humor: making it serious, like one of the Marvel Studios films, would undercut it considerably. You cannot shoehorn serious content into a show that does not take itself seriously. Third, the two aesthetics on violence would not synchronize: AoS is loathe to kill anybody; the team is not X-Force. The Punisher works when he is the cold vigilante type--one who would not fit in a program where nobody is killed deliberately and the heroes go out of their way not to kill anybody.
2. Narratively speaking, Coulson & Co. would not tolerate the Punisher. Even if the creative team somehow managed to shoehorn his murderous nature in, the episode would probably end with them submitting him to one of the detention facilities.
As for the networks that would adapt the program, I would hope it would not be AMC. Considering their mistreatment of showrunners - see the Walking Dead - I would hate to have an awesome series compromised by executives who disregard talent in favor of their own absurd notions. Thus, the only network left that would air a bloody, rated M punisher would be HBO. Their budgets would accomodate the character and their fearlessness in embracing mature content. Plus, their talent stable is pretty much unrivaled, when one considers all of the programs they have launched and resultant succcesses.
