I don't believe that for a moment. It's foolish to think an opportunity to grow in a different area is a sign of warning. They have tons of cash and are preemptively trying to find new markets before the stockholders bleed the company's profits dry because they aren't consistently beating estimates by huge factors anymore. Apple has almost 50% of their revenue coming from iPhone, that is a huge amount of risk for a company to have in an ever increasing market. It was only a matter of time.
A great example is google. Google is in tons of different industries and started in 1 major one. Do they look like they're failing anytime soon?
I think at this point you might argue that all of their products and services are similar or at least align with one goal. To which id say, cars are the next thing to be bombarded with tech that's now affordable for even the cheapest models. Gone to a car show lately? Every damn car has a damn back up cam and some form of a HUD. I think it only makes sense that they buy a successful company who already put up most the risk by starting a new company in a market place dominated by old hats. Tesla is now reasonably successful. Why not buy a car company and spread the brand to the auto industry, god knows apple would rather have huge margins and an extended brand rather than selling their software to gm for pennies on the dollar.