Lightroom editing is 16bits
I don't know what editing you are doing with layers, but it is my experience that only rarely will you be able to see a difference between 8bit layers and 16bit layers, and most of those cases where you will see a difference is recovering detail from highlights and shadows.
I don't work for Adobe, but I'd bet a huge amount of money that PSE will never go completely to 16bits. I think Adobe's philosophy is that if you want to use their top-of-the-line tools, you have to pay for their top-of-the-line tools.