Apple's (NASDAQ:AAPL) deal with China Mobile is finally sealed. "Apple and China Mobile today announced they have entered into a multi-year agreement to bring iPhone to the world's largest mobile network," read Apple's press release highlighting the deal.

iPhone 5c

The iPhone 5s and iPhone 5c will be available on the China Mobile's massive network beginning on Friday Jan. 17. Although every analyst seems to agree that the deal has positive implications for Apple, the extent of the estimated impact varies dramatically among analysts. In 2014, China Mobile is one of the company's biggest wildcards.

Varying estimates
Fortune's Philip Elmer-DeWitt has compiled analyst estimates of China Mobile's potential impact on iPhone sales in 2014. Of the 17 estimates he has collected, the average consensus for incremental iPhone sales in 2014 from the China Mobile deal is 19 million.

Far more interesting than the consensus, however, is the massive range of estimates. ISI's estimate, which comes in at the top, is 39 million. The lowest estimate comes from Morgan Stanley's bear case, at just 5 million. The disparity between the bullish and the bearish estimates isn't surprising. With 763 million total wireless subscribers, deriving an estimate from the massive number isn't easy; that's why the China Mobile deal is such a wildcard for Apple in 2014.

What kind of impact could 19 million iPhones have on Apple's bottom line in 2014? Morgan Stanley analyst Katy Huberty, who shared her assumptions regarding the potential impact on earnings per share, suggested that her mid-estimate of 12 million iPhones could boost Apple's trailing-12-month figure by 6%. Her bull case for 23 million iPhones could boost the bottom line by about 12.5%. Extrapolating from her assumptions, 19 million iPhones could add about 10% to Apple's bottom line in 2014.

Is 10% significant? Absolutely. Apple trades at just 14 times earnings; with conservative assumptions like this built in to the stock, the market doesn't expect much out of Apple.

Or here's another way to look at the benefit of a 10% boost to EPS: Apple is already a cash cow -- and it's only paying out 29% of its annualized earnings in dividends. Even more, Apple has about $149 billion in cash on the balance sheet. With a small boost to earnings, Apple's already very low payout ratio will decline even further; this gives Apple even more room to boost its dividend in the future. If Apple continues to grow EPS even at a conservative 5% annually beyond a projected minimum 10% jump in 2014 (thanks to a China Mobile deal), Apple could easily double its dividend without cutting spending in other areas. That would give investors a whopping 4.3% yield, compared to today's 2.15%

Of course the chance of this exact scenario to actually unfold is slim. But it is just one way to illustrate that low expectations for Apple's stock make even a 10% boost to EPS meaningful.

But given the gaping difference between high-end estimates and low-end estimates, China Mobile's exact impact is still an enormous wildcard for Apple shareholders in 2014. That said, it's a nice wildcard for Apple investors to have in their deck.