[SPOILERS for Agents of S.H.I.E.L.D. season 1 ahead!]
Marvel Studios and ABC's Agents of S.H.I.E.L.D. concluded its first season with a fair-sized bang; most important among the future developments it set up, is Agent Phil Coulson (Clark Gregg) rebuilding S.H.I.E.L.D. from a new foundation - even as less desirable side effects from the T.A.H.I.T.I. program responsible for resurrecting him, have begun to make themselves apparent. No surprise, Gregg is now suggesting that Coulson's evolution will continue (who knows, maybe it'll even speed up), over the course of the show's second season.
Throughout season 1 of S.H.I.E.L.D., many of Coulson's old acquaintances observed that he's "different" than the guy who hadn't been stabbed in the chest by Loki pre-Avengers - heavy-handed tactics, to be sure, as far as foreshadowing goes. Still, it's important to remember that such character development in season one's first half has already led to far more interesting developments in the show's universe (read: the Marvel Shared Universe), post-Captain America: The Winter Soldier.
Point being, there's no overlooking the fact that Coulson isn't necessarily still the same guy we all saw in Phase 1 of Marvel's Cinematic Universe - and therefore, the changes in his character and personality are bound to be reflected in how he goes about restructuring S.H.I.E.L.D. in the future. Gregg touched on that issue, when asked by IGN if "S.H.I.E.L.D. 2.0" will be "off-the-grid" and far less"officially sanctioned," than its predecessor:
"That's a really interesting point just because what's been clear to me is that the Agent Coulson who's running this team post-Captain America: The Winter Soldier, post-Hydra, post-being killed and brought back to life with something in him he doesn't understand… He’s a very different Coulson than the guy who everyone knew. A lot of people who knew him in the old days say, "He's different." I think you would have to be different having gone through that stuff. So I think he's reinventing himself and re-understanding himself as a person anyway, which is probably really necessary to taking in the new environment and figuring out what SHIELD ought to be in a way that it doesn't get rotten again."
As for those T.A.H.I.T.I. related side effects, which began to manifest themselves in unnerving ways with Agent Garrett (Bill Paxton) in S.H.I.E.L.D. season 1, that's bound to be a key factor in Coulson's arc during the show's forthcoming season. Gregg isn't spelling out just what to expect yet - probably because he doesn't know all the details himself yet - but he is teasing that you should anticipate something to come of the foreboding cliffhanger from the S.H.I.E.L.D. season 1 finale's credits (i.e. where Coulson started scribbling the same grid-like image that Garrett started writing after receiving a variant of the GH 325 serum).
"Well, Coulson got to watch himself pre-memory wipe describing why he thought the whole Tahiti Project was a bad idea. He was talking about all the things that were happening to the people they were using on it and why he suggested they can the whole thing - and looked pretty shaken while he was saying it. So I've got to suspect that some of the stuff he saw and some of those patients have some version of the stuff that's going to happen to him. So we go from having no SHIELD at all, with a director on the run, to a tiny Guerrilla SHIELD with Agent Coulson at its head, and maybe not in his own right head. That sounds fun. That sounds like an interesting Season 2."
Indeed, such a turn of events (see: unstable Coulson leading a revamped S.H.I.E.L.D.) would be in keeping with Gregg's comments about the show's second season being darker and more adult on the whole - in keeping with the trend of the post-Winter Soldier run of episodes in season one. Agents of S.H.I.E.L.D. really began to hit its sweet spot, once it shifted more towards being a serialized adult espionage adventure - still keeping things light enough to avoid alienating younger viewers - and it sounds as though season two is in a good place to keep that momentum going (albeit, without going too dark, that is).
Agents of S.H.I.E.L.D. season two will get underway on ABC later this year.