Strongest, i don't think so, but i always believed that oda had special plans for him. I mean the guy has one of the top 3 fastest growth rate of the serie, he went from being at the bottom of the fodder scale to trusted enough to deal with warlord in less than 3 years. He is being trained by the hero of marines and there's his dream of becoming admiral, he still got plenty of time to get there.
I don't see why in hell you would create such a character if you didn't want to give him a key role in the serie