McDonald's (NYSE:MCD) shares slipped today on the shocking death of Chairman and CEO Jim Cantalupo of a heart attack overnight. It's always sad, disconcerting, and frightening from a shareholder point of view when a company's CEO unexpectedly departs this earth. In this case, it could be seen as devastating, considering Cantalupo's transformation of McDonald's into a turnaround story.

When Cantalupo retook the helm in January 2003 after retiring from his leadership position for McDonald's International in 2002, McDonald's was struggling. For many, it seemed the death knell of a company that had lost its appeal.

Since then, it's been nearly impossible to keep up with all the strategic moves the company has made to return to viability. The "I'm Lovin' It" marketing campaign, Wi-Fi, and even musical downloads are helping it appeal to hipper, younger consumers and technophiles. Meanwhile, in what has likely been the bigger success, it has brought a more healthy angle to its fast-food appeal, with a range of initiatives including adult Happy Meals and serious menu changes, like the addition of white meat nuggets and the subtraction of "Supersized" fries.

I could go on, but you get the picture. Cantalupo's success in both getting back to basics and addressing important trends that could have made McDonald's obsolete when facing hungry competitors like Wendy's (NYSE:WEN), Burger King, CKE Restaurants (NYSE:CKR), and Yum! Brands (NYSE:YUM) has been evident. McDonald's monthly same-store sales and quarterly numbers have knocked proverbial socks off (though, of course, shoes are still required in all restaurants). The stock has risen 66% since Jan. 2003.

Most impressive of all, Jim Cantalupo forced many a naysayer to eat crow. Some pundits said he certainly couldn't transform McDonald's anytime soon, and some suspected maybe McDonald's was too far gone -- in reality, the transition took less than a year to pull off. If you'd like a recap on the remarkable doings of Cantalupo, rewind to last October, when Whitney Tilson nominated him CEO of the Year.

After today's sad news, McDonald's wasted no time promoting President and Chief Operating Officer Charlie Bell to the post. (In an interesting side note, Charlie Bell is one of those rare executives who started at the bottom of the ladder -- as a teenager, he became the youngest Mickey D's manager ever, at the tender age of 19.)

It may be tempting, but investors shouldn't give in to the gloom. While most stockholders face similar random risks, McDonald's investors may be in better shape than many other companies' shareholders would be under similar circumstances. Luckily, Cantalupo put the wheels of change into motion fast, and it's been clear what's been working for the fast-food giant. As long as the company continues to follow the course Cantalupo has charted, chances are investors will still find a lot to love in McDonald's.

Can McDonald's keep customers "lovin' it" without Cantalupo? Is the fast-food chain's recent success a clear blueprint for McDonald's management? Talk to other Fools about the tragedy on the McDonald's discussion board.

Alyce Lomax does not own shares of any of the companies mentioned.