Does it even matter who the parties nominate this year?!

In 2016, U.S. politics has become so polarized and partisan that (at least based upon the polls), it doesn't seem to matter who the Democrats or Republicans nominate for President.  The table below compares the RealClearPolitics average two-way matchups as of January 11, 2016:

RCP Average for 2016 General Election Matchups as of 1/11/2016

Clinton	45%	vs	Trump	43%
	45%		Cruz	46%
	44%		Rubio	47%
	45%		Carson	45%
	45%		Christie	44%
	46%		Bush	43%

 In each of these matchups versus the various Republican candidates, Hillary manages to get the support of between 44 and 46% of the electorate.  Versus Hillary, the various Republican challengers score between 43 and 47% of the votes.  Changing the name of the Republican candidate only varies the Republican vote by a total of four percentage points. (In all of these cases, the results are within the margins of error for the underlying polls.)

Sanders	44%	vs	Trump	42%
	43%		Rubio	44%
	45%		Cruz	42%

Similarly, Bernie manages to get between 43 and 45% of the votes against each of the Republicans, who get between 42 and 44% of the hypothetical votes. In each case, the number of voters preferring Sanders vs the Republican alternative varies by a range of only two points, which is exactly the result that Hillary obtained.

This seems odd, and it appears to be different than what the polling showed about the Presidential matchups during 2012, when different potential Republican challengers faired very differently against Obama:

RCP Average for President Obama vs. Republican Candidates in 2012 Race

Obama	49%	vs	Romney	48%
	50%		Santorum	42%
	52%		Gingrich	39%
	48%		Paul	40%

In 2012, the range of outcomes for the various Republican challengers vs Obama varied by nine percentage points, from a low of 39% supporting Gingrich to Romney's almost tie at 48%. (Of course, Obama went on to victory in 2012 with  51.1% of the actual votes to Romney's 47.2%.)

It may be worth noting that Florida Senator Marco Rubio is the only candidate who manages to beat both Hillary Clinton and Bernie Sanders in a head-to-head matchup.  I hope some Republican primary voters are paying attention.