What would happen to my disabled special needs adult son if I pass away in Houston, Texas, without a proper will?

I keep hearing that if I pass away without a proper will or plan in place, the state will step in and take control over my son’s care, even though I have two adult daughters. I currently have legal guardianship of my 26-year-old son, who has been medically diagnosed with Down syndrome and autism. He is non-verbal, has the cognitive abilities of a toddler, wears diapers, and requires constant supervision.

I’m deeply concerned about what would happen to him if something happened to me. I’ve always assumed one of my daughters could step in as his guardian, but people keep warning me that without a legal will or plan, the state might take custody regardless of family involvement. I’m unsure how accurate that is and would really appreciate some guidance or advice on what steps I need to take to ensure his future is secure. Thank you in advance!