President Obama's re-election has triggered panic in some GOP circles. Obama was able to win not just once, when Americans were reacting against the Bush era, but a second time, with a weak economy and a vulnerable record. America, the alarmists say, has fundamentally shifted so much that Republicans can no longer win national elections. This thesis merits serious consideration. Especially relevant is the fact that Mitt Romney's dismal performance among the growing Hispanic demographic made the race essentially unwinnable.

That having been said, Republicans' demise may not be at hand just yet. In the short and medium-term, it is worth asking how much of this victory can be chalked up to Obama's personal appeal and status as a historical figure, as opposed to fundamental shifts in the American electorate. The key question is whether future Democratic candidates will be able to command the type of margins Obama enjoyed among young voters and African-Americans. Although Republicans face long-term challenges with voter demographics, Romney's problem in this election may not have been primarily structural.

Democrats have consistently dominated Republicans among black voters in the modern era. They have also had the edge with younger voters. Obama significantly outperformed his Democratic predecessors among these groups, for reasons that seem obvious. But he won't always be on the ballot.

Take the black vote. In the six presidential races between 1984 and 2004, Republicans' support among blacks never exceeded 12 percent. But in 2008, Obama won them with an astounding 95 percent to 4 percent for John McCain. This time, he got 93 percent.

Romney received only 6 percent of the black vote. If he had gotten George W. Bush's level of support among blacks in 2004 (11 percent), he would have carried Florida and Ohio by more than 100,000 votes in each state. It's quite possible that Obama has found a Democratic ceiling with black voters, and future Democratic nominees cannot take such margins for granted. So although Republicans cannot afford to continue writing off black votes as they have for far too long, they probably still have time for a serious effort to win more of them.

The story is similar with the youth vote. In past elections, the under-29 vote has gone to Democrats consistently. John Kerry won this group by 9 points in 2004. Obama's great achievement was not that he turned out under-29 voters in significantly higher numbers but that he inspired so many of them. He won them by an astounding 34 points in 2008.

Obama has an unusually strong appeal with the young, but even his advantage among them shrank by 11 points between 2008 and 2012. Will the 2016 presidential campaign of, say, Martin O'Malley or Mark Warner appeal to under-29 voters quite so strongly? And what about black voters? Even assuming 2012 turnout levels for both groups, Obama would have certainly lost Florida, Ohio and Virginia if he had won just these two groups by the same margins that John Kerry did in 2004. And under such a scenario, had Romney managed to win 28 percent among Hispanics instead of his appalling 23 percent performance in Colorado, he would be the next president.

Republicans must take seriously their very real problems with black voters, young voters and also Hispanic voters. But they would be wrong to throw up their hands at demography as if the reaper had already arrived. There is still time for them to reach out. Democrats know they cannot take Obama-levels of support among these groups for granted, but Republicans will be done for indeed if they don't start working now to win their votes.