Its in style in past half year to be negative about Apple's future growth, because on a 'worldwide market share' basis its percentage of Tablet and Smartphone Sales has gone down in the first, and not grown as fast as Samsung's in the second. Because Apple is no longer growing at breakneck speed of over 50%, but rather last quarter Apple's sales only went up 18%. But even so, there's something odd, which is Apple's worldwide share of the Profits in Smartphones has remained same at over 70% (and far in excess of Apple's 20% unit market share). This is because much of the very fast unit-growth nowadays in both smartphones and tablets, is the explosive growth in low average income emerging markets countries. And that very fast unit growth in these low-wage countries is only possible for most of their citizens by introducing cheap products. Because these lower quality feature phones and tablets sell for low prices, and because there's too much competition at the "low end of the market", and the Dollar Volume of sales is less than Unit Sales market percentage, there's little profits there.
WHAT THE BEARS ARE MISSING IS: Apple can still grow at a nice rate, by aiming for 15 - 50% of advanced countries unit market share, countries like Japan and Australia and USA where incomes are higher and people are happy to pay $100 more and get a better and more reliable product, + aiming for a 5 - 20% unit market share of poorer countries smartphone and tablet markets. If Apple can get the top 10% of say China's 1 billion cell phone users to someday buy and IPHONE, that's still equal to its 40% share of the US Market. And what the Bears are also missing, is if Apple gets 10% of India and China's market by unit volume, but only selling High-End Phones, Apple will have 20 or 30% of the Dollar Volume of those markets and probably Half the Profits.
ITS THE OLD 80/20 RULE. 80% of Profits in a market come from the top 20% of Customers.