ND and NE are both weird -- Nebraska almost elected two Democrat congressmen in '06 and between them they have three Democrat Senators. I think in the end they'll go for McCain, but the Heartland can spring for charisma. I'm thinking about how Montana (which is similar to ND poltically) is now dominated by Dems on the state level, and went for Bill Clinton in '92.
As for Texas, it's not now and won't soon be a battleground state, but Texas is only really at heart +10 GOP, not +20. GOPers have been doing better than normal there, of late, partly because of the DeLay redistricting, partly because of the unbelievable incompetence of the TDP, and partly because Texans are proud of having a native son at the top of their ticket. With Bush leaving office, my guess is that Dems will do a little better there, but won't be able to present a credible threat to a GOP candidate.
The southern counties of Texas are now provinces of Latin America and the trend is moving north. In a generation or two it will follow California and Arizona.