EBay has had quite a run, but it is now entering a more uncertain future.

The online auction company provided disappointing guidance for 2008, overshadowing stellar fourth-quarter profits. And eBay confirmed that Meg Whitman would depart after 10 years as chief executive, to be replaced by John Donahoe, head of the core auction and ecommerce businesses.

The company said first-quarter revenue would fall far below Wall Street's average forecast of $2.14 billion, with earnings probably in a range of $2 billion to $2.05 billion.

EBay's outlook of $8.50 billion to $8.75 billion in revenue for all of 2008 also falls well below the $9.02 billion that analysts, on average, were looking for.  

Still, fourth-quarter 2007 earnings rose 53 percent from the quarter a year earlier, as non-auction income, such as PayPal, StubHub, and Skype, contributed some of the most robust growth for the period.

“We had a remarkably strong year from a financial perspective. We enter 2008 with our most diverse portfolio of ecommerce offerings ever—positioning us to drive long-term growth in the global ecommerce market,” Whitman said in a statement.

Jeff Segal, on Breakingviews.com, suggests that with a change in C.E.O., eBay should think about spinning off PayPal and Skype, as a way of unlocking value in the internet conglomerate. Indeed, he says, Skype, which caused eBay to take a write-down of $1.4 billion last year, might be a better fit for News Corp.'s MySpace or for Facebook.