Apple (AAPL 0.11%) has spent quite some time as the most valuable company in the world, although its run in the top spot has been periodically interrupted by Nvidia and Microsoft. Apple's market cap peaked at nearly $3.6 trillion, but it has since fallen back to around $3.4 trillion.When a company becomes that large and successful, it's natural that predictions about its future performance are going to be hotly debated. It hasn't helped the bull case for Apple that famed investor Warren Buffett has slashed ...