I believe Jobs left Apple with a multi-year plan before stepping down. However, the one thing you cannot plan around is how the market will change and how your competitors will change and improve their own offerings, and that is what is happening to Apple.
If you think about it, Apple is very much like the Dallas Cowboys. In the past, both were at the tops of their markets and had huge and devoted fan bases. Over time though, even the most die-hard fans start to lose their enthusiasm and blind devotion while more and more casual fans jump ship for the latest fads and trends.
Apple needs to launch a truly innovative product again like they have done in the past or they may find themselves falling faster and faster to their competitors. Their mobile devices like the iPod, iPod touch, iPhone, iPad, etc. and their computers like the Macbook Pro, Macbook Air, iMac, etc. were all innovative game changers or major technological leaps, and more importantly, they were new market creators. These days, their new products are just improvements on older products and ideas and in many cases now, they are the ones following the competition instead of leading it.
I hope they are working on one or more next-gen products and are just waiting to spring them on the industry and regain their position in the market. Otherwise, I have a feeling that Apple is going to continue their decline as their competitors take their place.