If you look at the history of companies that are formed and grow into large companies on the efforts of a dominant entrepreneur, they often languish or fail after the leader departs. The history of those companies is nowhere near as robust after the death/exit of the leader. A few recent examples are Howard Schultz leaving Starbucks (SBUX), and then returning to revive the franchise. Microsoft (MSFT) since the departure of Bill Gates has been mediocre at best - admittedly somewhat hampered by Gates's steady selling of shares over the years. Does anyone think that Berkshire Hathaway (BRK.A)(BRK.B) will be a better company after Buffett dies? One company that has been successful after the death of the founder is WalMart (WMT), but it is probably not coincidental that the family are still huge holders of the stock and involved on the board. Look what has happened to Hewlett/Packard (HPQ) after the founders died. Joe Wilson was a dynamic leader of Xerox (XRX) and created the research facility that Jobs and Wozniak used to start development of the personal computer, but later CEO's closed the facility believing that the research expenditure was not paying off. There are dozens of better examples that I am sure others can provide.
Back to Apple. Jobs was a design/sales genius who produced what the consumer wanted to buy. In some ways he was analogous to Pierre Cardin, Coco Chanel, Ralph Lauren, who have/had an innate sense of what will sell. Now that Jobs is gone his vision will live on for awhile. But his creative genius cannot be replaced. Tim Cook is an able lieutenant who will execute the plan, but he is not going to come up with the designs and visions of the founder. Apple will probably be with us 30 years from now. It is a large and successful company with many talented employees. But will Apple be a better company with Jobs gone? The price reflects to some extent the judgement of history. Without Jobs many years ago, Apple foundered. Although the backlog and products may continue to make it an outstanding company for the next few years, it is highly unlikely that it will be considered a great company ten years from now. The Apple difference is gone.