I would imagine Mario being hit hard with depression and actually take on villainous qualities. Bowser too would become depressed, but would give up conquering and just mourn the loss in his castle all alone. Mario would distance himself from Luigi; the green bro. would try to get Mario back to normal, but Mario would just reject his overtures. Eventually, Mario will take a step to the dark side. He kidnaps Bowser Jr. in the night, then sends Bowser a note, saying he is going to execute him at a certain time. In the end, Luigi has to stop his brother from commiting a terrible act. If this were a game, Mario would be the final boss, and would be the hardest boss of all time. As far as political ramifications, a militaritsic leader would probably rise up in the Mushroom Kingdom. The Toads would be tired out sitting around, waiting to be attacked by the Koopa Troop over and over again. They would start making preemtive strikes against the Koopa Kingdom. Bowser, in his depression, would be unable to lead. The Koopalings would try to hold things together, but splinter into factions are start in-fighiting, casuing a Koopa civil war. Just some ideas I'm throwin' out there.