Article I of the Texas Constitution, as it will read if approved by the voters:
Sec. 32. (a) Marriage in this state shall consist only of the union of one man and one woman.
(b) This state or a political subdivision of this state may not create or recognize any legal status identical or similar to marriage.
I am not leaving anything out. There is no section (c) to soften the blow.
It's hard to say what would be similar to marriage, but clearly, only one thing is identical to marriage, and that is...marriage. Hence, if the voters approve, the Texas Constitution will ban marriage.
As some wag said in the comments to another blog reporting on this, "we had to destroy the village in order to save it."
And if you examine it a little more, taking both parts (a) and (b) of the proposed amendment together, it would seem then that gay unions--since by definition they are neither marriage nor similar to it--would be quite legal.
"But...but...but you know what we _wanted_ to say!" True. And I am sure the Texas courts will be able to read the minds of the bigots who wrote the legislation, and make it come out as intended.