The Bottlecap lenses pop out. I would assume that means, in the future, Oakley will release seperate lenses for the frame. Is this assumption correct?

Not sure. All lenses pop out for the most part, but they don't provide that option.

I had a bit of trouble getting them out when I had tried. Just not as fluid as the HJ lenses.

The answers is yes. The bottlecap does have interchangable lenses, however oakley will find out the status of the product before they start making lenses.for it on a readily availible. They also do not want to kill the success of the HJ in building another product.

It was originally intended to be an interchangeable style, and the lenses pop out just as easily as on an HJ (except that the thicker frame doesn't flex as easily so it takes a little more force) but that's on hold because it seemed like it would work as a sort of fashiony alternative.

Likely, you'll never see retail lens kits like you do for HJ and M-frame.

Neil beat me to it, but the lenses do have the same tabs/wings on the corners as the HJ lenses. But, as said, Oakley will probably refrain from releasing retail lens kits for it. Which wouldn't stop any of us from having a few extra sets lying about.

Which brings me to my first thought on seeing them- I'd love to see them with a lens cut more like the non-XLJ Half Jacket.