The Weekly Standard's Jay Cost continues to crusade against the idea that demographic trends are slowly making the electorate more amenable to Democrats:

You see this over-confidence in subtle ways, most notably in what I would call the left's demographic category error -- whereby liberal analysts lump Hispanics, African-Americans, Asians, etc. into a "Non-White" category, which is then implicitly assumed to be a uniformly Democratic bloc. In response to the Census report, that's exactly what Christopher Beam of Slate does in this article, when he concludes:

Does that mean the country will become permanently Democratic? Of course not. Both parties will adjust to accommodate the shifting demographics. But Republicans will be playing catchup. The GOP will inevitably become more amenable to immigration reform, gay marriage, and separation of church and state, as their constituencies become more Hispanic, educated, and godless, respectively. Hispanics may not support Democrats forever—in 2004, about 40 percent voted for Bush—and some young Democrats will become old Republicans, but the blue team will have a lead.

Beam is following the basic script -- key Democratic groups, "non-white voters," college educated women, college kids, etc., are growing, so sooner or later the Democratic positions are going to win out.
I've addressed this broad argument several times before (see herehere, and here, for instance), so today I would just like to focus on this specific notion of the "non-white" bloc as it relates to the latest Census results, particularly to Texas, which is picking up four new House seats. I cannot state matters more plainly: Hispanic voters do not vote like African-American voters. The latter constitute a core Democratic group that systematically breaks 90:10 against the GOP, regardless of the political environment. Hispanic voters, on the other hand, comprise a swing group that currently tilts Democratic, but Republican candidates who are careful and considered in their appeals can make significant inroads into the Democratic margin. ...
It's worth mentioning another difference between Hispanics and African-Americans -- the latter group is uniformly Democratic across the whole country. African Americans who live in the rural South are overwhelmingly Democratic, so are those who live in the big cities in the North. Yet Hispanics are much more heterogeneous. You see above, for instance, the strength that Republican candidates have with Hispanics in Texas, and you could make a similar point about Florida. To these states we could also add New Mexico, where you really cannot win statewide without substantial Hispanic support, as well as Colorado, where John McCain won 38 percent of Hispanic voters in 2008. But Republicans do notably worse with Hispanics in California, and they are also weak with urban Hispanic voters in big Northern cities like Chicago and New York. In none of these states can the GOP reasonably expect to crack 30 percent of the Hispanic vote. Nevada, meanwhile, is a state where the GOP is slipping among Hispanics;  Bush carried 39 percent of the Hispanic vote in 2004, but Sharron Angle won just 30 percent in 2010.

I don't really follow Cost's  argument here.

He's refuting the notion that Hispanics are a 90% Democratic voting bloc like African-Americans. But nobody, including the foil he quotes, makes that claim.

Meanwhile, Cost's own numbers show that Democrats have been winning Hispanics by large margins -- even the states where he cites Republican "strength" among Latino voters are states where Democrats carry the Latino vote by a mere 20 points. The scope of those margins may fluctuate, but the basic fact is that Hispanics are a pretty strongly pro-Democratic voting group.

It's possible Republicans will increase their share of the Latino vote, but it's also possible that, as they continue to take hard-line policies on illegal immigration, they'll decrease their share. It's also possible that Republicans will increase their share of the black vote. Always in motion is the future. The overarching point seems to be that Latinos vote much more Democratic than the electorate as a whole, and their share of the electorate is steadily increasing.