Now, when the Democratic Party in Texas is nearly extinct, It's sure not extinct in counties with majority Mexican or Black electorate Dawg.
And the Mexican populace will only grow. You're ignoring all empirical data....especially nationwide. The Mexican vote for Dems in Texas will only grow from here on. Bush got higher than usual since he is native son but the only reliable "hispanic" conservative voters are Cubans (God bless em) and various South American professional expats. Soon enough Texas will look blue enough like the Valley and Bexar look now. 
You're ignoring all empirical data....especially nationwide. I'm not doing that at all. You are pointing to a static map. I am pointing to what has happened in a dynamic economy and society. Over 2-3 decades of a boom in Hispanic immigration, our country has done nothing but become more conservative and more capitalist. And the states where the Hispanic population has gone up are many of the states that have become much more capitalist (especially in the South).
Soon enough Texas will look blue enough like the Valley and Bexar look now.
15% Hispanic in 1976 -- Jimmy Carter
32% Hispanic in 2004 -- GWB (and Republicans state-wide)
Your theory has a million holes in it. Let me know when you can explain these away.