While I have no idea what TY is doing, I think you're mistaken that these is no reason. Once the 16x line no longer sells at a premium and the cost for production is the same or less compared to the 8x line, it would make sense for them to phase out the 8x line. Generally, speaking it's cheaper and simpler to maintain only one line then 2 lines.
Remember that 16x media can be burnt at 8x usually even though the quality mightn't be as good (especially with old burners and even more so with standaloneswhich probably haven't had their media codes updated in a while). The fact that the 16x line perhaps isn't as good as the 8x line and the 8x line would probably be better for people with 16x drivers who burn at 8x and for people with 8x burners (standalone or otherwise) is likely to be only of small concern of them. (Although of more concern then it would be to e.g. media code fakers).
P.S. Personally, I don't burn at 16x even tho I have a 16x burner but that's neither here or there