1) PowerPC is pretty alive and well. The Xbox 360, Nintendo Wii (U), and Playstation 3 all use PowerPC chips. There are a lot of these. IBM's Linux/AIX servers are all PowerPC and IBM incidentally makes the chips for the above game consoles as well. Not to mention the number of PowerPC chips in cars and other embedded devices dwarfs all the above in units sold.
2) Intel (probably) got out of the Xscale game not just because of hubris, but because it was necessarily enriching its competitor through licensing fees of the ARM architecture. Unless Intel could buy ARM, which it couldn't due to anti-trust, it should probably seek out a home grown solution instead of sealing its fate as another fab for ARM's designs. I'm not sure Intel didn't see the writing on the wall, it just failed to execute on a solution. Intel was probably very wary of trying to make a new architecture after the failure of the Itanium so it concentrated its efforts on a low powered x86 aka Atom. Unfortunately this was and still is a colossal failure. Intel still has no products for low powered devices and the arguments for an x86 solution are starting to fall apart fast.
3) Apple's success is a culmination of Steve Job's vision and Tim Cook's operational mastery. Apple's products before Tim Cook were beautifully designed, over priced, and under performing. Apple's product line without Steve Jobs was boring and unappealing. These last few years have been a golden age for Apple. To expect things to only get better from here would be to place all the emphasis on the company and ignore people inside it, not to mention history. I expect Tim Cook to keep Apple in a very competitive place while he's around, but companies have a tendency to lose their way. Just ask HP.