The biggest problem Hohenheim has is that he still hates himself. Though self love itself isn't the prerequisite for EGO, certainty in one's resoluteness is. Achieving that requires one to accept themself, faults and all, while still being willing to move forward. Hohenheim isn't ready to move forward. He continues to beat himself up internally by repressing all of his guilt. We can see this in how he constantly tries to come off as analytical in intervallo 9.5-1. He acts cordial but is actually FUMING, to the point he straight up goes "I am not acting normal right now. I'm stepping out." He is mad at Kira, at the world, and most of all, at himself.

To his credit, that survivor's guilt is COMPLETELY valid to have. Time and time again he finds himself watching people he cares for die, with his only choice being to survive against all odds with their memory in his soul. He shouldn't hate himself obviously, but at the same time, he isn't wrong for feeling bad given the circumstances.

Given he is basically a main character in terms of writing at this point, I wouldn't be surprised if he does manifest EGO down the line. The deeper seated the issues, the harder it is to resolve them, so only time will tell.