Yes the 6T has been discontinued in favor of the Verus Grand Tower. I do happen to have a pair here in open box stock if you are interested in them. They aren't in perfect shape and have some surface scratches, but they are literally the last pair I have. However most folks will find the 6T to be overkill for rear surrounds. You might think about a bookshelf style speaker like the 5B, or perhaps a bipole speaker like the 4BP. Another option would be a smaller tower like the 4T or 5T.
I hope that helps but please let me know if you have any other questions, thanks!