Never, ever, ever say "never" when it comes to tech. In 10-20 years they'll be handing out 8 GB USB drives in gumball machines for 5 cents each, and 16 TB flash drives will be $15 on amazon.
If we have the optical technology to render a certain number of floating gate transistors in a certain area, we also have the optical technology to render 10-100x as many bits of raw data in that same area.
The "blu[e]" in blu-ray is a reference to the shorter wavelength of read lasers (relative to CDs/DVDs) necessary to cram more data on a disc. Trying to cram 100x as much data onto a single optical disc layer would require use of a laser with 1/10th the wavelength that blu-ray uses today, which would incur all sorts of additional costs and complexities. Granted, it might be possible to use other techniques (deep layering, holographic storage, etc.) to side-step such problems, but who knows what the limits are? It's telling that there isn't much research into next gen. optical storage compared to other storage forms.
Additionally, increasingly people are embracing form-factors for computers that do not accommodate optical drives (smartphones, tablets, ultrabooks), which helps drive R&D money into the forms of storage that are more popular.
My point is that one cannot firmly say, a priori, that one format will "never" be cheaper, larger, more popular, etc. than another. Technological progress is rapid in storage.
Because optical storage as a technology (R&D) has died, with optical drives starting to be removed from laptops and soon-ish desktop PCs in favor of flash, and mainly internet downloads/uploads. Bluerays are a dead end -- movie distribution will be (is) on the cloud. Ditto for music. Ditto for data.
Even HDs are on the way out, to be replaced by SSDs in the coming 5-7 years.