I just rewatched the beautiful piece of art that is Agents of S.H.I.E.L.D. Season 1, Episode 17: Turn, Turn, Turn. As we know, Ward reveals his true colors at the end of the episode by executing Victoria Hand to save John Garrett.
I wanted to pose the thought experiment: what would Ward have done had Garrett perished during the Battle at the Hub?
Ward begins his betrayal of the team out of his loyalty to protecting Garrett. I am reminded of a quote he says in the next season: "I was never loyal to HYDRA. I was loyal to Garrett" (S2E03). We see him prove this in Season 2: he readily betrays Bakshi, only gets close to Whitehall to bring Skye to her father, and then allies himself with Coulson against HYDRA. He only becomes a HYDRA leader out of spite for Kara's death, not for any ideological reason.
Additionally, when the HYDRA Uprising began, Ward had not yet revealed his true allegiance, had developed feelings for Skye (enough so that he later questions and challenges Garrett), and felt a genuine camaraderie with Coulson's Team (which he claims to regret destroying, S2E19).
So in a scenario where Garrett, seemingly Ward's only anchor to HYDRA at the time of the Uprising, was removed from the picture, is there a chance Ward would have abandoned HYDRA altogether?