Actually, the number of primary voters is no indicator at all about the general election. Again, let's look at 1988 where 23 million voted in the Democrat primaries, while only 13 voted in the Republican primaries. Yet Bush destroyed Dukakis in the general election.
I agree polls about November mean nothing at this point. But once the glamour of Obama starts to fade, the public will turn to the serious candidate and that is McCain.
Don't ever underestimate the Republicans at turning on the attack machine. Look at how they were able to turn John Kerry who actually served in Vietnam into a traitor while they were able to make George Bush who couldn't even show up to serve in the National Guard in Alabama into the true patriot.
A black guy who has the most liberal voting record in the Senate, dad was a Muslim, middle name is Hussein, belongs to a church that is proudly ethno centric etc. The Republican National Committee will have lots of fun with Obama before it is all over.
There will also be a segment of the Democrats led by the Clintons who will also work behind the scenes to see that Obama loses so Hillary can come back in 2012. Don't for a minute think the Clintons care about anything but their own power and won't be doing everything they can to help him lose.