Once the children of illegal immigrant (who are themselves citizens) are old enough to vote. Texas went from 61% R in 2004 to 55% R in 2008, while the white vote remained at 75/25 R. As another poster would say, be patient.
This was because the "favorite son" vote actually helped Bush a lot in the Rio Grande valley (much less elsewhere); it is almost impossible to imagine Cameron County coming even close to voting for a Republican not from Texas, but it happily voted for Bush in 2004. In the long-term, yes, as the second and third generations grow up, the state will become more Democratic. However, this needs to be coupled with a weakening of the GOP in the suburbs to tip the state to the Democrats.
Happily voted for? He won it by a margin of 1% Fix your wordage dude. Even if Bush being from Texas helped him in the border counties, they're not highly populated.
It's not a big deal we went from 61% to 55% in Texas. We did worse in almost every state. What do you expect. As it stands now, Obama is highly unpopular in Texas. We'll bounce back nicely in 2012.