Honestly, I could see Hillary being the Democratic John McCain should she run. She will be a party elder whose relevance is fading and has to continuously shift her positions and sacrifice her ideas to keep up with the ever changing and evolving party, very possibly against a younger and more charismatic opponent like Rubio.
I don't think so; the Clintons are more popular right now than at any point post 1998. In 2004, nobody was excited at the idea of McCain running in 2008. #Hillary2016 is already trending. She will disappoint a lot of people if she doesnt run. She is more liked and respected now than in20078. Hillary would be the first woman President. Her candidacy would far different than it was in 2008 and than McCains was. What is funny the 2016 Republican field, with Paul Ryan, Marco Rubio, John Thune, etc is almost certainly going to be younger than the 2016 Democratic field. I think a better comparison for a potential Hillary 2016 campaign is George H.W. Bush in 1988, to be frank.
Ryan, Jindal, and especially Rubio honestly cannot win. For all the appeal of Rubio on paper, the guy is a tea partier. A tea partier will never win a general election, especially with popular former President's Obama and Bill Clinton campaigning hard. That is the Republicans problem. Obama won because he was a "movement" guy. The tea party stands for ideals which mainstream America will never accept. Ryan will be a much more formidable candidate than Rubio for that simple fact. Even if Rubio would likely win Florida, his standing in the remaining swing states would be quite weak.
Obama's reelection is certainly evidence that Bill Clinton's influence is extremely high. Clinton gave Obama the post debate bounce. Obama will more than likely be viewed more favorably in 2016 than he was in 2012. These 2 guys will almost assure Hillary wins should she run in 2016. Young people don't just vote for other young people. The past 6 years have seen the younger vote only increasing for the Democratic candidate - this generation is just about lost to the modern day republicans.
I think the 2016 Democratic field will be quite predictable. If Hillary runs, I think you will see few other democrats come in to really challenge her. If she doesn't run, the female NY senator, Sherrod Brown, Deval Patrick, Joe Biden would all possible names. Tough to know who to favor. I think Hillary easily wins the nomination if she runs, though.
Republicans, it is Christie, Jindal, Rubio, Ryan, and a few others. Rubio's charisma is overrated (he is seriously nothing special at all), and he is a tea partier. Jindal is the same. Ryan, you can see the future but his views may be too conservative. Chris Christie is the probably the best bet. I see the primary season being long and drawn out, again.
TBH, a Ryan/Christie ticket is probably the Republicans best bet. They both seem very fit for the roles. I would bet it is Clinton vs. Ryan in 2016, with Hillary winning. Doubt she loses in 2020 either. The economy would be due for a drop around 2024, PERHAPS the republicans will have changed enough by then to really compete.