Jobs was erratic and irrational and relied on Charisma.
Cook is probably a nicer and better boss than those at Google. Balmer, Larry Ellison and Elop.
The Touch Screen Smart Phone is a mature market now like that for the Mac Laptop or iPod or iPad. It's impossible to predict what the next success for Apple will be or if there will be another like iMac, iPod, iPad and iPhone. An Apple TV or iWatch won't be it. Probably not an iPippin either.
They would be mad to try and complete on price with entry level tablets, phones and "notebooks". Cook will probably try and maintain the Apple Marketing Ethos and Apple as the world's most successful niche consumer media electronics company. Jonathan Ives isn't even really a true HW designer. He is a stylist and even admits he copies and admires Dieter Rams. Having him set the look and feel of the GUI as well as the package is a good idea. Having him run Apple would be a disaster.
Apple products fill a niche in the market. I personally find them a bit expensive and limited as I'm a poor engineer. Nor do I update my gadgets because a new version arrives but because the old one is unrepairable.
We are probably at Apple Peak, but I think that would still be the case if Jobs was in perfect health and magically 10 years younger too. It happens to almost all companies as a market becomes mature. RCA was once a Behemoth, but "died" 1986. Today it's just a badge. A future start up becoming the size RCA was or Apple is is unlikely to be selling Radios and TVs (RCA) or Phones. The iPhone + iPad likely now dwarfs iPod and Mac profits to small change and iPhone much more than iPad.
The iPhone came just as more powerful ARM, commodity Phone chips and larger Displays were easy to integrate. They could only have done it so well at most a year earlier. Also a big ingredient was widespread network upgrades and good data plans. Without the Data Plans the iPhone would have been merely a phone with local media player. albeit with a sensible GUI (though Trolltech had demonstrated similar a Phone edition touch GUI to replace their WinCE like PDA edition first!) That "trick" can only be done once.