I wouldn't expect a new console before 2015 and I expect another MK before that.

Yeah, I don't believe that. Microsoft is working on a new console right now, and this gen has lasted longer than any other gen. By 2015 it will be a decade old. There is no way I see that happening.

My prediction, they announce new consoles at E3 2012. The consoles then launch in fall of 2013.

I kinda think this gen is gonna be around for a bit longer than 2013. That's just my guess though

I disagree. I hate launch titles. First of all, during the launch of a new generation, the games never take the full advantage of the console's capabilities, mostly because they're unaware of how far they can push it.
Second, upon launch, oftentimes, there are problems with the consoles. Sometimes they break down, or glitch out, or have a lot of bugs and freezes. These are the reasons why I never buy a console at launch, and I certainly wouldn't want a new Mortal Kombat game to FORCE me to buy a new console at launch.
I'd rather they made another one toward the END of this generation, and as the new generation of consoles came out, they started working on a game, and about a couple of years into that console's existence, put out something that truly shows off what that console is capable of.

Yeah Microsoft has publicly stated that they expected the Kinnect to extend the life cycle of the 360 for another three to five years. I'm not saying you're wrong, I'm just saying I wouldn't hold my breath especially given the amount of money Sony and Microsoft have both lost on their hardware. To launch new hardware at a time when the current hardware is finally seeing a return is fiscally irresponsible.