well of course, it be like the fight with hiruzen and orochimaru..... no master ever wants to fight their student to the death
at first minato would try to reason with him and if that didn't work i belive he would have killed him cause as hokage he had to protect the village.... not to mention he tried to take his son's life
If he knew it was obito he would talk to him and try to reason him but nothing would have changed. There is a chance that obito would tell minato the whole moon-plan-thing and everyone would be better prepared for akatsuki
obito obsessed with rin i mean madara didn't even try to persuade him that much he was already rdy to fuk the world for some bitch, and she didnt even love him thats whats ****ed up, she was into kakashi, but minato would have probably spanked him harder if he knew it was him
Like others have said not much would change besides the fact that Minato would try to reason with Obito at first but I do not believe Obito would listen and as Hokage, Minato would do his job and the fight would happen between the two.
i think minato would have used his forbiden sealing jutso that can take away memories to brainwash a certain person against obito to change him just like minato did to naruto and yamato in the movie the lost towers