I'm sure Blackberry thought the same thing about 4 years ago.
The smartphone business is all about momentum. Blackberry had the same attitude years ago when they were on top (that they were #1 and didn't need to innovate anymore). Just because Apple is the #1 smartphone maker by a wide margin doesn't mean that their market share can drop rapidly. Because smartphones iterate so quickly, Apple had better be on their game or they can lose significant share in a year or two while others make big strides.
And you seriously think Apple, one of the most paranoid companies on earth, will let themselves end up like BlackBerry?
Not that its a market share game for Apple. Its never been.