You're right, CompUSA won't go out because macs arent there, but think of the rest of the reasons:
1. In that industry (large technology superstores aka bestbuy/sun/office max/staples...) most big corps don't last very long. The max is around 10 years. I see CompUSA near the end of their tenure.
2. Look at the computers that CompUSA offers. Only HP, Compaq, and Sony. The only reputable brand there is Sony, with HP and Compaq having reliability problems plaguing their systems since the beginning of time. Customers know that even though their computer systems are getting better. Every customer comes in and says somthing about a friend who had an HP or Compaq that sucked. CompUSA lacks Dell computers, the largest computer seller in the world.Dell systems are simply too good, and other companies can't compete. I had a Dell once, and everything about it was great. Especially the customer service. They are unrivaled in today's failing customer service age.
3. Prices change too quickly for retail stores to keep up with, and because of that prices are usually higher than online stores. Prices are also higher because CompUSA has to deal with a middle man reseller usually, and nowadays consumers are getting educated on the internet, and are willing to purchase through it.
CompUSA does not and will never depend on Macintosh sales to stay afloat, it is the multitude of other reasons will throw CompUSA under in this next decade.
-Pete