Like it or not, here they come.

As of this year, the so-called Millennials (born from 1980 to 2000) are the largest generation in the U.S. work force, according to Pew. They represent one out of three workers, and they're climbing fast. Soon they'll be taking over management positions en masse.

Whether you're cowering in dread at their coming, or cheering in the corridors at the latest regime change, Millennials will soon be in positions of power--and they'll be making changes. Like every generation before them, today's young business leaders are reworking old management practices and tired leadership truisms to better suit their needs and preferences. So what's going to change? Experts agree on a few broad themes.

1. They'll kill work-life balance ...

Ever since Gen X came into the work force scarred by memories of their parents' long hours, we've all been talking constantly about work-life balance. But Millennials are going to kill the term. Which doesn't mean they aren't going to grapple with the same issue of puzzling out how to spend their allotted 24 hours a day. They're just approaching the problem differently.

"They don't mind accessing their work life during their personal life, but they also want to access their personal life during work," author Chip Espinoza tells Fast Company. In other words, balance is out and blend is in.

2. ... but insist on flexibility.

But while this generation may be willing to stay constantly connected to work, they are demanding a price for all that late-night emailing, and that price is flexibility. "A lot of people now are [always] connected; they're checking email after hours," Kathryn Minshew, CEO and founder of The Muse, told CNBC. "If companies are going to ask that much of people, they have a responsibility to give more as well. I think that means giving people the opportunity to have a flexible workday."

3. They'll lean on metrics.

If Millennial managers aren't going to be counting hours and checking attendance to make sure people are working, what will they do to make sure all employees pull their weight? Expect more of an emphasis on metrics and less on face time, experts agree. "This generation of managers is going to identify metrics that determine whether people are productive," Espinoza predicts, adding, "things like key performance indicators will continue to be a movement."

4. They'll support employee growth.

Millennials may have gotten a reputation as a bunch of job hoppers, but in all fairness, that's not entirely their fault--they faced some atrocious economic conditions and have learned the hard way that loyalty is dead and changing jobs frequently is a necessity. But this familiarity with the need to move often will have an upside when they get into management. They're great at understanding and supporting employees' personal development.

And if Millennials also get a bad rap for understanding work as all about their personal self-actualization rather than their employer's needs, then at least this also has the same upside. As managers, they'll be just as keen to see their team fulfilled as they are anxious to make sure their work aligns with their personal goals.

When the Hartford's 2014 Millennial Leadership Survey asked "how an employer could demonstrate it was invested in helping them advance at the company, more Millennial respondents chose training and development, feedback and coaching over cash incentives," CNBC reports, for example.

5. They'll (finally) kill the performance review.

They've been the walking dead of the business world for years, but it looks like annual performance reviews will finally be put out of their misery by Millennial managers. Why? Millennials are too hungry for feedback to wait a whole year (or even six months) to get it--or give it.

"As a Millennial, I like to generate ideas, flesh out part of my plan, and then get feedback from my manager. It's against my nature to do something methodically (and patiently!) and then present him with one final, polished product," confesses Emily Disston, director of HR at BetterCloud, on The Muse. "Why? Because I desperately want to get feedback (OK, also praise) along the way for motivation--and so I can integrate that feedback into the final product."

"Traditional semiannual reviews are too infrequent for Millennials," agrees Jay Gilbert in Ivey Business Journal. So what will replace them? That's still to be seen, but the smart money seems to be on some combination of more frequent coaching and quick and constant tech-enabled feedback.

6. Everyone will know what everyone else makes.

There have been some experiments with radical transparency when it comes to salaries already, but Brazen Careerist co-founder Ryan Healy believes it's inevitable that the idea will become mainstream.

"The vast majority of the world's under-30 population are living their entire lives online. Transparency is no longer an option," he has written. "Websites like Glassdoor and PayScale let you compare your salary with others in the industry. My company, Brazen Careerist, practices complete transparency. Even financial gurus like Suze Orman say it's great for business. As Gen Y continues to work our way up the ladder, it will just be a matter of time before companies of all sizes have transparent salaries."

7. The line between contractor and employee will blur.

What's another of Healy's predictions? With the rise of independent workers and remote teams, the distinction between freelancer and employee will no longer be as distinct as it once was.

"Companies will begin to think of their contractors as their employees," he believes. "When Brazen had a big budget, we worked with a ton of contractors. When people asked how many employees we had, I would always mention that our team felt much larger because of all the freelancers. As the number of independent contractors increases, they will become a vital part of the team."

What predictions would you add to this list?