Well, according at a post at PCMAG.COM (which is here), apparently not in any time soon:
"I've recently been over in Taiwan, and the manufacturers don't have a road map for 56X," says Brad Yeager, a marketing manager at Memorex. "In order to make 56X blank media, you need a much flatter disc and new molding, which costs more."
Apparently, we face the same problem now as we did in 1998, where it just wasn't profitable to create media and drives that performed reliably at increasing speeds. Things seem to have reached a bit of a plateau for now in the CD-R arena. And it will probably take a consumer market that demands to be able to write faster before we will see these increasing speeds. More here.
Personally, its a rare day that I find CD-R media that writes faster than 24x anyway. Meaning that I should have just gone for the much cheaper 24x CD-R writer and not the 48x. What about you?