English has been this vacuum cleaner of a language, because of its history meeting up with the Romans and then the Danes, the Vikings and then the French and then the Renaissance with all the Latin and Greek and Hebrew in the background.
Texting has added a new dimension to language use, but its long-term impact is negligible. It is not a disaster.
Sending a message on a mobile phone is not the most natural of ways to communicate. The keypad isn't linguistically sensible.
Language has no independent existence apart from the people who use it. It is not an end in itself; it is a means to an end of understanding who you are and what society is like.
Text messaging is just the most recent focus of people's anxiety; what people are really worried about is a new generation gaining control of what they see as their language.