I do agree that Oguri Shun is a great actor, but there are some things that do not transition well. Was his performance as Nanba Mutta the best? No, it wasn’t terrible either though. Gintoki however is a different character altogether. Do I think there is a possibility for Oguri to play the role correctly? Yes, but a lot of it also depends on how they design the script, which will almost definitely use action as the selling point. However to put all of the load onto one main character who is a great actor doesn’t bode well either. My main point however is that Gintama is a show that might have the hardest time being adapted to Live Action.