Except Apple's customer base isn't becoming smaller. The PC industry is shrinking year after year, and Apple is the only PC maker demonstrating any growth at all. And they are consistently the dominant tablet/PC-replacement maker.
Your doom and gloom predictions are scary, but don't seem to fit with reality.
I'm not trying to argue with you because this is marginally true but based upon sales of one year to the next of each manufacturer so Apple although growing as a percentage does not equate to that many people buying Mac's as compared to the millions of PCs sold.