Facebook is tightening its grip on Instagram

Instagram will soon be without its founders for the first time ever.

With CEO Kevin Systrom and CTO Mike Krieger leaving soon, the future of the photo-sharing app will be much more controlled by Facebook executives, which could have big implications for the service.

News of the departures sent shockwaves around Silicon Valley, primarily because it was so unexpected. Though it's common for founders to depart a company after an acquisition, Instagram's founding duo has long been an exception.

The abrupt nature of the news itself, which broke late Monday night, immediately gave rise to rumors that the resignations had come as the result of some greater falling out with Facebook's upper management.

Systrom was scheduled to keynote next year's South by Southwest, and had other speaking engagements lined up for the coming months. What's more, Instagram only just opened a new San Francisco office, a decision that was driven, at least in part, by Systrom's desire to cut down on his commute and be closer to his family, according to a Wall Street Journal Magazine profile published today (Systrom's resignation came after the story had gone to press, according to the WSJ.)

Meanwhile, Mark Zuckerberg, who often pens effusive send-offs for high-ranking execs, issued an unusually brief statement, which was not published on his Facebook page or, notably, his Instagram account.

And while it's not clear if there was any one cause for the sudden resignations, multiple reports indicate that Systrom and Krieger had grown increasingly uncomfortable with Facebook executives' involvement, and their efforts to bring the two services closer together. Both Recode and The Wall Street Journal pointed to Facebook's recent change that removes any reference to Instagram when users share photos from Instagram to their Facebook profile.

What happens next?

What all this means for Instagram, the service, remains to be seen, but it suggests there will be many more changes to come. Most obviously, Instagram will be under new leadership for the first time in its history.

Facebook hasn't commented publicly on who will replace Systrom as Instagram's top executive, but most signs suggest it will be the newly installed VP of Product, Adam Mosseri. The exec was formerly in charge of Facebook's News Feed, and has increasingly become a more public face for the social network. (Mosseri is active on Twitter, where he regularly engages with journalists, and has made an effort to cultivate closer relationships with publishers.) He's also a trusted lieutenant for Zuckerberg.

There have already been a number of signs that Facebook is eyeing more ways to tie-in with Instagram. The company has been experimenting with putting its notifications inside of Instagram, which has been unpopular with some users. And the app currently has a prominent "open Facebook" prompt.

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Without Instagram's founders to push back, it's difficult to imagine there won't be even more Facebook-ification coming to Instagram.

For Facebook, these measures likely feel like necessary steps.

The company is facing more public scrutiny than ever, and mounting distrust from users who are wary of the social network in the wake of the Cambridge Analytica scandal and Russian interference in the 2016 presidential election. The service lost users for the first time in its history last quarter, and its stock still hasn't recovered from the subsequent crash.

But the last two years have also coincided with the meteoric rise of Instagram, which has grown to more than 1 billion users. The app, which rarely released updates in its first years as part of Facebook, began pumping out new features to boost that growth and engagement.

As things have gotten worse for Facebook, it's become more and more clear the company is relying on Instagram's success. The app has managed to remain relatively scandal-free, compared with Facebook, and, unlike Facebook, it remains incredibly popular with teens and younger users.

It's not surprising that the company would opt to tighten its grip on the photo sharing app at this particular moment. It needs Instagram more than ever before.