Of course Apple has had past failures. That proves my point about them trying to be innovators and creating products that didnt necessarily have a market like the Newton. It was a failure because it was way ahead of its time and the techonolgy didn't yet exist for it to be nearly as useful as the iPad. It's easy to say after the fact, when something is a smash hit like the ipad, "oh there was always a huge market for tablets". I'm sure at some point in the future Apple (or another company) will create a product that is a failure. I think you're failing to fully grasp what motivates Apple, historically. They have always tried to come up with products that are new and innovative as contrasted to MS who tries to cater to the masses with a mediocre product that just performs adequately.
When MS does try to branch out from their comfort zone, they give us failures like W8 and the surface. Lol
What motivated Apple to make an iPad mini is they saw consumers buying other 7" tabs. What motivated Apple to make iPhone 5 bigger is they saw consumers buying bigger phones. Of course, Apple has done innovating of its own. But it's not guaranteed future success just because of current success. That's true of any company. That's why no one can afford to fall behind.