Take a look at the phone manufacturing industry. There used to be Siemens phone, Sagem, Trium, Panasonic and until recently, Nokia. Then industry grew so competitive that companies whose core business wasn't phone manufacturing got seriously burnt. The same is happening in the computing hardware industries. HP, Alcatel, IBM and other companies who were trying to do it all, manufacturing everything from computers to printers, are now dying and having to pick one line of business to focus on.
It's only in Africa and Asia that the biggest companies are the ones attempting to do everything: from petroleum to noodles. It was like that too in US 100 years ago. But now the world is converging really fast, specialized companies are no longer limiting themselves to their local market. They now aim at the entire global market. Google is now eating deep into our advertising industry, taking more adverts placement than any other company in Nigeria. Chinese manufacturing companies are making the textile industry and electronics manufacturing industry unprofitable for any indigenous player.
Specialized computer language programmers now make more money that general practitioners (a multi-skilled doctor). Footballers make more money than the business professional whose CV is 12 pages long. Today's heroes are those who picked a path and went a mile beyond everyone on that path. If you want to remain relevant and not have to fight wolves on all sides, then pick a particular career or business path, resist the temptation to spread yourself too thin and go the extra mile.