I'd sell all the IPs off, half to Sony, half to MS, and watch the fanbases split and intensify the console wars. So what, you say, whoever gets Mario wins. In a surprise twist, I would sell the rights to make Mario platformers (2D and 3D) to...a popular iPhone dev of some sort. All the other IPs are split...including the Mario sports games, Party, etc. I'd put a stipulation in each contract stating that only Capcom may develop a Smash Bros game and can draw on all of Nintendo's IPs whenever they want to make Smash Bros games. The Smash Bros games have to be multiplatform on PC, Sony, and MS consoles.
basically, I'd make a bunch of money and make the industry a lot more interesting.