The Dow Jones Industrial Average (DJINDICES:^DJI) has seen plenty of executive-level turnover lately. Two Dow components have switched nameplates on their CEO offices so far in 2014. In less than three years, the Dow has replaced 10 of its 30 top executives, with tenures ranging from four to 14 years.

So there's plenty of fresh blood leading the market's biggest blue chips right now. Even so, a handful of Dow Jones CEOs are getting very long in the tooth.

These are the two longest CEO tenures on the Dow today. Will these chief executives still be around in a year or two?

Cisco Systems CEO John Chambers. Source: Cisco.

John Chambers is only the third CEO in the 27-year history of Cisco Systems (NASDAQ:CSCO). Having assumed the CEO title in 1995, just as the Internet started breaking into the mainstream of business and society, Chambers has steered Cisco through 19 years of fantastic success. That includes torrential returns for longtime Cisco shareholders:

CSCO Chart

CSCO data by YCharts

At 64, Chambers is pushing retirement age. There was a time when critics were calling for his head, regardless of tenure and age, but those cries have faded into the background.

Chambers has been talking about retirement since 2012, and inside sources recently said an announcement is heading our way. By the end of 2014, Cisco seems likely to have a new leader.

When that happens, the company will probably pick a new CEO from its strong insider ranks. That has become the standard procedure for blue-chip tech companies on the hunt for new leadership lately. Tech companies on the Dow have replaced four CEOS in the last three years. All four of these races were won by longtime insiders, with no superstar outsiders taking the top jobs.

American Express CEO Ken Chenault. Source: American Express.

At American Express (NYSE:AXP), Kenneth Chenault has held the CEO office since 2001.

Chenault's 13-year reign hasn't been quite as impressive as Chambers' dynasty at Cisco, but then he never took over a brand-new business on the verge of a major sea change. American Express shares have still largely tracked alongside the Dow under his leadership, and are currently running way ahead of the blue-chip index.

That being said, American Express has seen mixed results during Chenault's tenure. Revenue has increased slowly, and free cash flow has been hit and miss:

AXP Chart

AXP data by YCharts

I'll note that Chenault has worked under some tough conditions, with the 2008 economic breakdown falling in the middle of his CEO term. But the company has lagged far behind its largest rivals on both the top and bottom lines.

Chenault is a solid if unspectacular leader, and at 63 he's staring down that dreaded retirement deadline. Still, American Express tends to hang on to its CEOs for a while. Predecessor Harvey Golub held the title for eight years. Before him, James Robinson owned it for 16 years.

So it's kind of a toss-up whether Chenault will retire soon. Payment services are heading for a huge makeover in this increasingly digital and mobile age, and maybe it's time for new thinking at the top. Chenault comes from a Harvard Law background, and this could be the perfect time to introduce a new American Express CEO with more of a technology focus.