On one hand, it's impossible to predict what is going to happen in four years. In 2003, President Obama was a state senator. In 1989 there was no buzz about Bill Clinton as the next president. By the same token a candidate who looks appealing today may, four years from now, look like yesterday's news. An up-and-coming candidate, a fresh face and voice, may start to look older, stale, unaccomplished. The dangers of what can happen over four years seem to be particularly pronounced for Republicans, given that there's now a significant part of the Republican base that is offended by political compromise. The Republican Party as a whole has reaped significant reward for being "the Party of 'No'", but that approach is not particularly helpful to a candidate who wants to build a record of accomplishment, or to somebody who has to appeal to a national audience as opposed to the voters of a particular state or district.
The "dream" candidates on the Republican side, the candidates that sat out the present race but are depicted as possible contenders in 2016, include Paul Ryan, Chris Christie, Bobby Jindal, Marco Rubio, Tim Pawlenty, Rob Portman, Jeb Bush, Nikki Haley, and Bob McDonnell. I think some of those candidates are lightweights whose inclusion in the list serves to highlight only how the media and party can sometimes elevate mediocre people to undeserved heights (no offense, Paul Ryan), but there is something you can draw from that list: Unlike the majority of candidates in the present primary, most of those potential candidates are viewed as having some level of genuine substance, and moderate to strong understanding of the issues facing their states or our nation.
If you are of the opinion that the Republican Party's strongest candidate looked at the 2012 campaign as one the Republicans were destined to lose, it makes sense that the "better" candidates would sit out the race. The problem with that theory is that after the 2010 midterm elections and with the nation's sluggish recovery from recession and the housing bubble, this should have been a great time for a strong Republican candidate to run for the presidency.
The Republicans need to consider the factors that kept what many believe to be their best candidates for winning the White House from joining the 2012 campaign. If it turns out to be that their various litmus and purity tests allow Rick Santorum and Michele Bachmann to be taken seriously but exclude Bobby Jindal or Rob Portman, that's something they need to consider. There was room in the 2012 primary season for serious policy discussions between the candidates. It would have been interesting to hear a serious debate between Jon Huntsman, Ron Paul and Mitt Romney, but neither Huntsman nor Paul were deemed sufficiently serious as candidates by their own party. A Romney victory could reinforce that effect in 2020. A Romney loss might bring about a different approach to the primary in 2016, but I'm not holding my breath.
Again assuming President Obama is reelected, the Democratic race for the nomination promises to be an exercise in contrasts with the Republican contest. Possible nominees include Andrew Cuomo, Martin O'Malley, Hillary Clinton, Mark Warner, Kay Hagan... some of whom are anything but household names. And again, let's not forget the "Bill Clinton" effect - the strongest candidate for either party may not be on our present radar - and that some candidates who presently look reasonably strong will no longer look like serious contenders when the primary season begins. But one thing seems clear, the Democratic race will be between candidates who will be addressing actual policy issues. You may recall from four years ago that addressing the issues sometimes brings more heat than light, and is not always done well, but I don't expect that you'll see anything approximating the "bubble candidate of the