HP tech support told me that there will be a retroactive hardware fix at no charge. They said the parts will be available in late December or early January.
I called HP Support today to inquire about the status of the new rollers since I had no luck printing on the new Harman FB Gloss. My first level support person, Jen, put me on hold for about 4 minutes and then came back and said I would have to prove a roller mark issue on HP media to be eligible for the retrofit. I explained how the Z3100 was specifically designed to allow use of 3rd party papers and that I knew the rollers had been redesigned to accommodate the new FB glossy papers among others based on user feedback. She said "sorry, that's the policy" so I asked to be bumped to the next support level.
A few minutes later, James got on the phone and spouted the same line about only supporting HP media. We had a friendly discussion where I simply repeated the mantra "but the Z3100 was designed specifically to work with HP and 3rd party media" about 7 or 8 times after which he agreed that I could have the retrofit when it was available. It took a while, but he finally fessed up that it should be in a week or so. He agreed to give me a case number with notes to the effect that I was approved for the retrofit when I called in next time so I could avoid all the HP defenses against providing its customers with engineering improvements to the printer.
Don't take "No" for an answer, but stay friendly and calm if you have to deal with this.