Could have been? Easily. Hiruzen, a Hokage himself already confirmed that he had long since possessed the wisdom and intelligence to be Hokage. Since he was seven years old.
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By the time he was was an adult his wisdom and intelligence had only grown. This is made evident by the many shinobi who praised Itachi's intelligence among other things, as well as the statements Itachi himself would later go on to make. This being the most famous one.
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He would have had more than enough skill to become a Hokage as well. With just 3T he makes top tier shinobi look like a Genin. His skill with Genjutsu, and base Shunshin speed decides most battles before the opponent even knows it has started. Then there's still Kenjutsu, Shurikenjutsu's, Katons, and Suiton. He definitely has the power.
Depending on what you believe his illness to be, there's a chance that would not be a a factor in this situation. For example, I'm of the opinion that the illness comes with usage of the Mangekyou, so it is not a problem here. He wouldn't have obtained MS in this case after all, and therefore been healthy. Then of course, there's the fact that he was able to take care of himself well enough to survive so long with such a detrimental illness. With that in mind, Konoha doctors could likely even have cured him.
If his only competition would be Obito and Kakashi, then there is no competition at all. We can ignore Obito completely right away, the manga has already proven him to be nothing more than a subpar ninja without Hashirama's DNA, Madara's personal training, and MS. None of which he would have possessed in this scenario.
Kakashi has already made clear that he had no desire to be Hokage whatsoever. If we as assumed he did however, Itachi would likely have been selected over him. The Uchiha were considered to be powerful and elite. Itachi was elite even among the Uchiha. With the clan and Konoha still in good standing with each other, it's a fair assumption that Itachi would have been a rather popular candidate. His record is more impressive than Kakashi's despite Kakashi's own above average history.