FORTUNE – When Eastman Kodak filed for bankruptcy in January, no one was surprised. The 131-year-old company once controlled 90% of the U.S. film market in the 1970s, only to be displaced by the rise of digital cameras. It took decades for Kodak to fall.

Now a similar kind of long, slow decline may be afflicting printer industry. And Hewlett-Packard (HPQ), long the market’s giant with a market share above 40%, may be approaching its own Kodak moment.

Printers have long been a cash cow for HP, but they are losing popularity as people share pictures in the cloud, looking at them on tablets and smartphones. The decline has been increasingly evident. HP’s printer and imaging division has seen its revenue decline by 12% since its 2008 fiscal year. The group comprises a smaller portion of revenue – 20% last year, compared with 31% for PCs and 28% for IT services – but it’s historically had fatter profit margins.

MORE: Inside SAP’s radical makeover

But even those profit margins aren’t what they used to be. The printing division’s operating margin was 15% of its revenue in fiscal 2011, still much better than the PC division’s 6% margin. But it’s down from the 18% operating margin that printers saw only two years ago.

And if that’s not bad enough, the decline in HP’s printer business seems to be accelerating. In its most recent quarter, the company said printer revenue declined 7% from the same quarter a year earlier. Operating margin for the division dropped to 12%. Why the sudden decline? During the holiday season, fewer shoppers bought printers – consumer printer revenue slid 15% on year.

HP’s new CEO Meg Whitman, who calls the printing division “the lifeblood of HP,” responded to the decline by folding it into the PC division, which saw a 15% drop in revenue last quarter. That will solve one problem: concealing the extent of the decline in HP’s printer margins by blending it with lower-margin PCs. More practically, it could give HP greater leverage in negotiating prices with component suppliers.

MORE: Another HP org change

HP made a similar move under Carly Fiorina years ago, but her successor Mark Hurd split up the two divisions again. Whitman is trying to do more than simply rearrange deck chairs, but investors want bolder action.

Small surprise, then, that Wall Street was hardly impressed by the move. Needham & Co. felt any gains would be “subtle” and slow to materialize. Morningstar found it sensible if “far from game-changing.” Goldman Sachs found it “modestly negative” because the two divisions had few strategic gains.

Most worrisome to some, was the retirement of Vyomesh Joshi, who led HP’s printers during three successful decades but was retiring at the moment secular changes are hitting. Then there was this historical tidbit an Evercore Partners report titled “Making Changes that Don’t Really Change Anything”: In 2005, then-CEO Carly Fiorina combined PC and printer businesses too, only to see the work undone by her successor, Mark Hurd, six months later.

MORE: HP: Same issues, different year

The slowdown in printer sales is hitting HP at a tough time. Whitman is trying to do more than rearrange HP’s deck chairs, she’s trying to make bold moves to eliminate the company’s weaknesses and focus on its strengths. In an earnings call last month, Whitman noted that HP had been slow to respond to fundamental change in its core markets – from PCs to printers to services. Last week, she said that “everything is on the table” in the reand did little to dispel reports that significant layoffs are coming.

HP has been through six CEOs (including two interim chiefs) in the past seven years. Last week marked Whitman’s six month anniversary on the job – half the tenure of her predecessor, Léo Apotheker. Reviving HP is a tough task that would take years under the best of circumstances. Doing it while the cash cow is ailing is going to make the task that much harder.