From my perspective, the Sinai is a net drain for Israel really: no rapprochement with Egypt, damaged relations with US, and a hostile populace leading to the possibility of a prolonged war like Lebanon (think how ISIS is there right now, which would only expand if they were fighting against a Jewish authority).
But what if Israel doesn't return Sinai, what would happen? The above may not be so much of an issue because of its sparse population. Could the area become more Jewish over time if settlers are brought in?