Yes, but won't the change still mean that those districts will still elect 5 Republicans and 1 Democrat (E.B. Johnson)?
Maybe Kenny Marchant ends up in a primary with Pete Sessions...
No. Definitely not necessarily. Bonilla will end up in a far more marginal district - something much closer to the one he barely won in 2002, and in the other direction they might also end up with a district very similar in demographics to Lampson's old district in the Houston area.
PS. It's also quite likely that Bonilla & Cuellar could end up in the same district again, that being a district similar to the 2002 district, in which case Bonilla will be very hard-pressed to win again IMHO.