There's very little to say right now about the 2016 general election. I'm not going to say that there's no point at looking at changing demographics, or early financial mobilization, or whatever, but almost all of what you're going to read in 2013 and 2014 about the 2016 general election is going to be useless.
In particular, speculation about the electoral college is mostly a waste of time. So are the specific comparisons of how this or that candidate would do in the general election; even to the extent that candidates can matter, which is limited, it's very unlikely that we can say very much about how Chris Christie would do compared with Marco Rubio, or how Hillary Clinton would do compared with any of the alternatives. At least I'm not aware of any evidence that there's much of anything we can say at this point. It's also surely the case that most of the events of 2013 are going to be long forgotten by November 2016; not only the gaffes, but even substantial things such as votes in Congress and how laws are implemented. Well, not all of them will be forgotten, but few will have any effect on the 2016 general election vote. ACA implementation is a terribly important story, but will it change votes in 2016? Probably not. And probably not in any way that's easy to predict from where we sit now.
Again: that's not true of the nomination contests. Because, remember, the choice between Ted Cruz, Marco Rubio, and Scott Walker is a very difficult choice for most people who will be making that choice; the choice between (say) Cruz and Clinton, or between Chris Christie and Amy Klobuchar, would be a very easy choice for almost everyone.
So, yeah, go ahead and focus on the nomination contests...but it really is too early to be talking about the 2016 general election.