Texas German is spoken by the fifth and sixth generations of early German immigrants to Texas. In interviews with some of these people in a BBC piece (here), we discover that future generations of these families are unlikely to continue to speak German. The people interviewed (probably in their sixties) said that they had spoken nothing but German in the family when they were children, but after the War many Texan Germans preferred to speak English to their children.
Professor Hans Boas of the Linguistics Department of the University of Texas has been recording the speech of Texan Germans, and has established that a) there are many variations within the language - the German of no two speakers is identical, and b) it is different from the German spoken in Germany. Mouth movements have been affected by the speakers' knowledge of English, and English vocabulary has crept into the language, as in the sentence "Die Kuh ist über die fence gejumpt" (the cow jumped over the fence).
Here's the short description and video.