You know what's been going on with Sonic. After Sonic Adventure 2, Sonic stared getting worse and worse with each main 3D installment until it hit rock bottom with Sonic 06. After that, the quality started getting better and better (Colors vs Generations is debatable) for most fans, but most people seem to think Lost World is a step down. What do you think it would be like if Mario was in this situation? Answer away!

Same.

Probably switch over to the PC Master Race unless its only Mario and every other Nintendo's franchiese are still golden

A series of subpar games and franchise mismanagement? Mario would fade faster than you can say 'Luigi'. He's not cute, he's not blue, and ... he's not cute. As a straight-up character, he's pretty forgettable.

that would never happen.besides sonic generations was good

It would just be Mario.

Miyamoto would jump off his roof.

Nintendo would go belly up, at least on the console side of things, because Mario is the only thing keeping the Wii U afloat at the moment, and barely at that. The handhelds have Pokemon and other franchises to keep sales relatively healthy, but if Mario main games and spinoffs started becoming really mediocre and run of the mill, then Nintendo goes the way of Atari and SEGA in the console department.

Nintendo fans would cry on forums about how Mario used to be the shit... Also, Miyamoto would try to kill Iwata.

Mario wouldn't be in Sonic's situation. Nintendo doesn't rush games to meet deadlines - Sonic Team started with Sonic The Hedgehog 3 and Sonic & Knuckles being split into separate games. Stupid ideas and characters aren't implemented on a regular basis - Sonic Team started with Knuckles' Chaotix and never looked back.