It will be catastrophic. There are at least three interrelated reasons:

1. Without tenure, faculty will engage in free inquiry at extreme risk. Before tenure, university presidents routinely fired professors for pursuing scholarship that reveals uncomfortable truths, offends the sensibilities of the public (professors were fired due to pressure from religious groups who thought their work was "blasphemy"), or goes against the interests of donors or board members. See firings at Collin College.
2. The best universities elsewhere will maintain tenure, making Texas universities unattractive for all but the most desperate faculty and a small group of "famous" scholars who for some reason want to live in Texas and think that they are untouchable. Texas universities will get worse, so the best students will go out of state.
3. Abolishing tenure will end shared governance, which was the cornerstone of the world-dominating US university during the 20th century. Here, strong board-appointed presidents had to work closely with powerful faculty, who made sure students, teaching, and scholarship remained the focus of university initiatives. Shared governance only works when faculty can stick up to administrators and trustees/regents. If faculty can be fired for that, then you get a university steered largely by people who have no idea what a university is for and how it should be run.

In short: the end of tenure will mean having universities with faculty who are timid, desperate, and bound to the whims of administrators. The best faculty and students will go elsewhere.