I said much the same things immediately after the 2000 and 2004 election. Hispanics are not a crucial "swing" vote. They're more of a "flow" vote in that they tend to go with the flow of their white neighbors, just consistently farther to the left. (For example, the high point for the GOP in share of Hispanic vote in House elections was Newt Gingrich's 1994.)
We hear much obsessing over the Hispanic vote, but some of that was a smoke screen made up by Karl Rove. Rove's two big successes — 2002 and 2004 — stemmed from mobilizing heavy turnout among white voters and winning a high share of whites. But you aren't supposed to talk about appealing to whites, so Rove did a lot of hand-waving about how Republicans were going to win via Hispanics, and a lot of innumerate journalists bought it.
McCain, the chief Republican spokesman for amnesty in 2006, did poorly in motivating whites to show up and vote, and did mediocre in attracting whites votes, so he lost. Having an economic crash right before the election and the pointlessness of his own campaign other than as a celebration of his vanity no doubt doomed him anyway, but one obvious lesson is that being a famous amnesty enthusiast is a net loser for a Republican candidate — it doesn't motivate Hispanics (who aren't very excited about making illegal immigration easier, and the ones who are are going to vote Democratic anyway) and it depresses non-Hispanic whites.
In the long run, of course, due to immigration and affirmative action, it's hard to see any successful GOP strategy other than a national version of their success in the South, which is based on carrying 75 percent of the white vote. I think the country would be better off with a competitive two party system in which whites were widely distributed among the two parties, but in the long run, that's unlikely to happen due to immigration. We'll either end up with a competitive system with most whites in one party, or we'll end up with non-competitive, corrupt one-party dominance by the Democrats on the model of the Chicago Machine writ large.