Instagram’s founders are finally leaving Facebook, six years after they sold their startup to Mark Zuckerberg. We’ll skip the drama of their departure in this post. This is about keeping a great thing going — and how Facebook could potentially mess it up.

Instagram is, in many parts of the world, the most culturally relevant technology since texting. And that has everything to do with its founders — Kevin Systrom and Mike Krieger — and their teams, who have meticulously shaped it since creation, executing near-flawlessly with tight control.

Walking through the things that make Instagram so special — its network, product, experience and institutional taste — it’s easy to see vulnerability in the wrong hands. Facebook can’t afford to screw this up — especially now, as it increasingly relies on Instagram for growth and for engagement from younger users.

Instagram’s network — its users and their follower relationships — is by far its most valuable asset.

Instagram is special because the most interesting people in the world, and in your life, are on Instagram, posting the most interesting things that are happening to them (or a mundane slice of reality, depending on the day). That’s the biggest reason Instagram Stories was able to leapfrog Snapchat Stories so quickly — because the network was already there to adopt the format.

Instagram has consciously but subtly steered its services to focus on your actual friends and not the influencers or brands you follow. It is nice that Instagram seems to know my wife is my wife (possibly from our Facebook metadata?) and always plays her Stories first. But those influencers and brands matter, too. I want to see what’s up with the random Japanese artists, Nordic designers and French chefs I follow. Or Instagram wouldn’t be nearly as good.

Crucially, it matters that your Instagram network is different from your Facebook network. There is likely some overlap, but not complete overlap. Facebook is your phone book; the social utility. Instagram is for people whose food porn, sunsets, midlife crises and baby videos you actually want to see — the interest graph that speaks to your soul. It would be a big mistake for Facebook to try combining those things any more, or to shove random Facebook friends’ stuff into your Instagram feed. Please don’t.

While famously minimalist at launch, Instagram has evolved into a surprisingly complex, sophisticated app without feeling overwhelming or cumbersome. In addition to being a creative outlet, it’s now an important communication, search, discovery, bookmarking, storytelling, marketing, recruiting, education and entertainment product, and could become a leading e-commerce engine. There are ads, but they mostly feel native and not too annoying. And it’s still easy to find things!

It’s not always perfect — the recent IGTV bolt-on feels more desperate than it should. But overall, Instagram’s product evolution has been excellent — including the things it hasn’t tried to do, like games, an “app platform” or too many formats. It’s been significantly better, in my opinion, than the Facebook app, which has long felt bloated. And don’t even look at what Facebook Messenger has turned into in its quest to become WeChat.

Quality, too: Instagram is arguably the best-built big iPhone app, and that matters. The second-biggest reason that Instagram Stories was able to leapfrog Snapchat Stories overnight is that it was built better — everything about it was just nicer. But when Facebook cloned Stories for its own app, it was noticeably less elegant than Instagram’s copy.

Facebook is no slouch at this stuff — its speed and reliability has long been a trademark, and its sense of visual and interaction design is better than most. But Instagram’s execution and balance have been on another level. Let’s hope that continues.

This is where Facebook may be most tempted to change things. Now that Instagram’s founders are gone, is there any reason to keep it effectively running as a subsidiary instead of as a department or function of Facebook?

I don’t know enough about the day-to-day process similarities or differences in how Instagrammers and Facebookers work to predict how cultural integration would go. But when I visited their respective headquarters a year ago, I saw companies from two different planets. Facebook’s office felt like I’d landed in a fancy Mars colony. Instagram’s felt like I was visiting Condé Nast.

To the creative set, Instagram is just cool in a way that Facebook could never be cool. It’s why people treat it differently, and I think a big part of why they’ve continued to embrace it. They know Facebook owns it, but they let that slide because Instagram has continued to be cool. Facebook is Mark Zuckerberg standing in a theater of VR-headset-wearing zombies. Instagram is Kevin Systrom at the Met Ball. It’s not bad to be Facebook (minus the Trump-Russia thing, I guess), but it has been very, very good to be Instagram.

For the near term, it’s likely that Instagram’s network and product will keep it going strong. (It’s not like there’s a suitable alternative!) Many interesting and talented people still work there and won’t necessarily follow the founders out the door. But over the years, it’s crucial to keep a strong sense of identity of what it uniquely means to be Instagram or it will lose its magic. Who will do that? Is that something Mark Zuckerberg cares about?

Apple has largely kept its impeccable institutional taste after Steve Jobs’s death because Tim Cook is a very classy CEO, and Jony Ive and his industrial design sensibility have long been the driving force of the company. So things keep going. YouTube has also done well since its founders left many years ago — credit to Google — so there’s hope.

I wonder how that will work — or if it can — at Instagram, as the two guys who’ve led everything it’s ever been are leaving, abruptly, together.

This article originally appeared on Recode.net.