Yes, but as I pointed out, the other 49 states require the Congress's consent. Texas already has that check-box filled. You even quoted the part where Congress agreed to it already. That's what makes Texas's situation different. All that's left is an act of the Texas state legislature (which will probably never happen as you stated).
Ok, I'm going to try one more time, and then I give up.
Texas has ALREADY been divided into 5 states -- New Mexico, Colorado, Wyoming, Oklahoma, and Texas. That's why the northern border of the panhandle is at 36 degrees north and thirty minutes. The Missouri Compromise said states north of that had to be free states.
I guess we'll have to have differing opinions on what the situation is.... It would be an interesting court test if it could ever come to that. I haven't really searched but it would be interesting to see other stated opinions from law groups on what would be required.