Employee handbooks are not binding on a Texas employer. The typical employee handbook says the employer will not fire someone until that person has been verbally warned, and then warned in writing a few times. Or, the handbook may say that an employee will not be demoted or fired without a good reason. Once upon a time, such handbooks were found to be binding upon the employer. Employers soon learned, however, that they could avoid the binding nature entirely if they simply state in the handbook that it is not binding and that the policies can be changed anytime.
So, yes, these days, almost every employer, probably 99.9% now state somewhere in their handbook that it is not binding. So, yes, an eleven year employee can now be fired with no warning simply because a new manager wants to downsize the office.
I have previously talked about employee handbooks here and here.