The world Bob Iger made

There were the times when it seemed like Walt Disney CEO Bob Iger might be the last Hollywood executive standing.

Yes, Iger's been openly thinking about retirement and searching for a successor - a search that culminated in this week's announcement that he'd be stepping down from the CEO role immediately, with Disney Parks Chairman Bob Chapek succeeding him. (Disney says Iger will remain involved as executive chairman and will continue to "direct the Company's creative endeavors" until the end of 2021.)

But Iger's succession planning hasn't stopped him from solidifying Disney's dominance of the entertainment business, a position designed to last long after his departure.

Acquisitions have been the cornerstone of that strategy, with Disney acquiring Pixar, then Marvel, then Lucasfilm and most recently a big chunk of 21st Century Fox. More than anyone, Iger seemed to understand that the Hollywood studios' continued success would depend on their intellectual property. It's no longer enough to just to make a successful movie or series; a successful studio needs to own IP that could fuel cinematic universes, TV shows, theme parks, toys, games and more, indefinitely.

To be clear, even before Iger, Disney was no stranger to mining IP for both box office success and its broader corporate aims. Nor was he the only Hollywood executive to pursue these strategies over the past decade. By now it's a well-worn observation that virtually every big-budget Hollywood film is either a remake, a sequel or an adaptation of existing material.

Disney CEO Bob Iger immediately steps down from CEO position

But Iger was the one who made the biggest bets, repeatedly, and for whom those bets seemed to pay off most impressively and consistently. That's clear when you look at the biggest box office successes of 2019 - Disney released seven of the top 10 films, with another ("Spider-Man: Far From Home") benefiting from Marvel's input and audience goodwill.