They would have been badass and would have been kage material, their chakra would have been atlest equal to tobirama. Kawarama looks as if he'd have a personality of the2nd and itama looks as if he'd have the same motives as the 1stBut what could they had done?
Brothers alot of people have missed out on kawarama senju, (hashi had four brother's, these two died)Hashi's brother would have definitely impacted the story if he grew up and became at least a Tobirama tier shinobi (capable of going head to head against MS users). If Tobirama dies then his brother would have become the head. The problem is we don't know what he'd do as a village leader, persecute Uchihas?