As I am not an American - a neutral perspective.
Firstly I wouldn't make any predictions at this stage, it is too early to make a sound judgement.
Watching the primaries though there seems to be a trend to, let us call it, "purism". Many Republicans seem to want a "real" conservative, which is why Cruz is so popular with them. Many Democrats want a "true" liberal, which is why Sanders is doing so well.
Assuming those two went on to win the nominations, Donald Trump might take umbrage and run as an independent. Meanwhile Michael Bloomberg is making noises that the centre is not going to be represented and he could make a run as an independent as well.
Which gives you four serious candidates (I know that in every Presidential election, there are more than two candidates, but you never hear much about anyone except the Republican and Democrat running - not even the Libertarian or the Green Party candidates get much consideration).
If this happens, this could end up being very complicated!
Living in Germany these days where there are five major parties (and a sixth potentially emerging), this isn't so strange to me personally, and run-offs are sometimes needed when an out-and-out winner is required (as happened in Frankfurt in the last mayoral election). Americans may though find the whole thing rather strange. If nobody wins an outright majority in the electoral college, what happens then?