Everything changes for Samsung's foldable phones tomorrow, September 9. Since 2019, Samsung has dominated this industry without facing any competition from its largest rival, Apple.

Galaxy phones already face an uphill challenge in convincing people to shift from their iPhones. Foldables haven't faced this dilemma thus far, because if an iPhone user wanted a foldable, Samsung was the only viable alternative. Apple will now close this route forever when it launches the first foldable iPhone.

The foldable iPhone arrives nearly eight years after Samsung introduced the original Galaxy Fold and took the first major step toward turning foldable phones from a futuristic concept into an actual consumer product.

Credit where it's due: Samsung got there first. It took the gamble, endured the early challenges, refined the technology and spent years trying to convince consumers that a phone that opens into a larger screen was worth having.

Apple now gets to walk into a category that Samsung has matured and tell everyone what a foldable phone is supposed to be. This is now Samsung's biggest challenge in the foldable segment. The Galaxy Z lineup's closest competitors are no longer devices from Chinese OEMs that can't even sell in the United States. They'll now be devices that carry the enviable iPhone brand.

Apple has an extraordinary ability to take something that already exists and make it culturally significant to a much larger audience. The iPhone wasn't the first smartphone, nor the Apple Watch the first smartwatch. In those, and many other categories, Apple didn't need to be first. It just needed to make people care.

That's precisely what Samsung needs to be thinking about tonight. Perhaps that's why it has announced the launch of a global campaign to show the world that it's been making foldables for far longer than Apple. It has done the hard part of making foldables credible as a category. Apple gets to benefit from that momentum by leveraging its massive brand loyalty to challenge Samsung's lead.

There's a lot to play for in this category. The foldable phone market is still tiny in comparison to the conventional smartphone market. While Apple's entry will give a major boost to the category, it's not like people will no longer buy Galaxy Z foldables.

The Galaxy S series continues to hold its own against the iPhone by being the flagship Android smartphone to beat. We may see a similar picture emerge in foldables, where foldable iPhones become a leader in their own right while the Galaxy Z series leads every other Android contender.

There's a case to be made for Samsung welcoming this growth. A rising tide lifts all boats, and if the foldable pie increases because of the iPhone, there will be opportunities for Samsung to sell more units as well.

Samsung is also in a unique position of benefitting from Apple's success in this segment. Its display division will supply millions of foldable panels for the iPhone, as it already does for many of Apple's other products that have OLED displays.

Samsung may also sell additional components such as batteries and memory chips, which will only contribute to the conglomerate's bottom line.

What Samsung cannot and must not do is rely on the fact that it was there first. As the dominant incumbent, it can't rest on its laurels. Since 2019, it has been trying to convince people that they can make the shift to foldables by leaving behind the comfort they've developed with conventional phones.

It now has a much bigger job, which is to show people why Galaxy Z phones remain the better choice even after foldable iPhones hit the market.

Apple doesn't need to spend as much time as Samsung did in convincing people that foldables are the future. Its late entry is testament enough that if Apple deems a category worth joining, it's mature enough. All it needs to do is make consumers view the foldable as the obvious next step in the iPhone's evolution.

That is the real significance of Apple's September 9 event. Samsung started this story in 2019. It spent years writing the opening chapters. Tomorrow, Apple gets to pick up the pen and rewrite history.