Starbucks Executive Chairman Howard Schultz is preparing to step away from the coffee chain he built into a global behemoth – and stoking speculation about a possible 2020 presidential run.

Yet, in the era of real estate magnate-turned-President Donald Trump, Schultz is just one of several business titans whose possible political aspirations might influence the next campaign for the White House.

For more than two centuries, most candidates for U.S. president had some public or military service on their resume before mounting a successful bid for the White House. But Trump's election in 2016 has opened the door for an extensive list of wealthy business titans who long to notch a place in history.

"There's a huge barrier that Donald Trump tore down," Jeffrey Sonnenfeld, a senior associate dean at the Yale School of Management, told CNBC. "And that pathway is now open for the Mark Cubans and the Bob Igers" to consider running for president.

Schultz left the door open to a run Tuesday, although he stressed that he's exploring all of his options for public service.

"There's a lot of things I can do as a private citizen other than run for the presidency of the United States," the Starbucks executive said in a CNBC interview. "Let's just see what happens."

Read more: Howard Schultz could have access to a superior campaign war chest come 2020

But experienced politicians aren't about to step aside at the first sight of another billionaire candidate with tons of personal funds on hand.

Here are some of the professional politicians and business players who are widely speculated to consider challenging Trump for the White House in 2020 – and how they stack up in the money race.