And I've been hearing experts such as yourself make this argument for years now. So if the demographics have been shifting so dramatically, why did Bush increase his margin in Virginia? WHY?!?!?
Based on Census Bureau statistics, the demographics of VA have changed significantly. In 1990 the population of VA was 6,187,358, which included 4,791,739 whites; 1,162,994 blacks; and 159,053 Asians or Pacific Islanders. Hispanics of either race numbered 160,288.
In 2006 the population of VA was 7,642,884 which included 5,413,295 whites; 1,496,076 blacks; and 365,515 Asians or Pacific Islanders. Hispanics of either race numbered 470,871. The growing minority population, a normal Dem constituency, has a political impact. There has been an increase of approximately 840,000 in the minority population out of the total population increase of 1.4 million.
The Bush margin of victory in 2004 [8.2%] did not represent a statistically significant difference from the margin he won by in 2000 [8.04%]. And McCain is not Bush and Obama is not Kerry. It is a whole different dynamic.
In the VA Dem primaries 1 million voted for the Dem candidates compared to the 1,454,742 that voted for Kerry in the 2004 general elections in VA. Elections are about turnout. Although VA does not have registration by party and has open primaries, this is a huge turnout for the Dems in a primary. In 2000, Gore received 1,217,290 votes in the general election in VA. If the Dems can turnout the vote for the general election like they did the primary, they are going to be very tough to beat.
If the demographics have shifted so drastically from 1990 to now, we should see it reflected in Virginia's voting patterns. We haven't, not when comparing Presidential elections. And for those folks who want to bring up the last two governor's races and the most recent Senate race, my response is "So?" Something like 6 of VA's last 9 governors have been Dems. The Senate seats have been mostly split during my adult lifetime (and I'm graying in the temples). Only recently (2003?) did the Pubbies capture the House of Delegates, IIRC, for the first time in eons (rhetorically speaking). VA is not a "GOP" state. But it is a GOP state for Presidential elections.
I truly don't care about the primary numbers. That's pure speculation. The Dems had a contested race, the GOP didn't, and any voter can cross over and vote in the other primary. Could it be indicative of trouble? Of course. And it could be nothing more than bored Pubbies and Operation Chaos.
Of all your arguments, only one concerns me. And it concerns me in many states, not just Virginia. That's Obama's ground game. If it's as good as advertised, it could be a long election night.
The rest of the arguments I heard in 2000 and 2004. I expect similar results in 2008 - although a few points closer, and I don't really expect the Obamessiah to pull out of the state prior to the election like Kerry and Gore (I think) did.