One of my favorite patterns in our industry is when the old and established are wiped out by disruption, irrelevance, or changing fashions. Like a forest fire, clearing out the old is very destructive and shouldn’t be taken lightly. But what’s left behind is a clean slate and immense opportunity.

I don’t think we’ve ever had such an opportunity en masse on iOS. After what we saw of iOS 7 yesterday, I believe this fall, we’ll get our chance.

The App Store is crowded: almost every common app type is well-served by at least one or two dominant players. They’ve been able to keep their leads by evolving alongside iOS: when the OS would add a new API or icon size, developers could just add them incrementally and be done with it. Established players only became more established.

iOS 7 is different. It isn’t just a new skin: it introduces entirely new navigational and structural standards far beyond the extent of any previous UI changes. Existing apps can support iOS 7 fairly easily without looking broken, but they’ll look and feel ancient. Their developers are in a tough position:

Most can’t afford to drop support for iOS 6 yet. (Many apps still need to support iOS 5. Some unlucky souls even need to support 4.3.) So they need to design for backwards compatibility, which will be extremely limiting in iOS 7.

Most can’t afford to write two separate interfaces. (It’s a terrible idea anyway.)

Most have established features or designs that won’t fit well into a good iOS 7 design and will need to be redesigned or removed, which many existing customers (or the developers themselves) will resist.

I don’t think most developers of mature, non-trivial apps are going to have an easy time migrating them well to iOS 7. Even if they overcome the technical barriers, the resulting apps just won’t look and feel right. They won’t fool anyone.

This is great news.

Apple has set fire to iOS. Everything’s in flux. Those with the least to lose have the most to gain, because this fall, hundreds of millions of people will start demanding apps for a platform with thousands of old, stale players and not many new, nimble alternatives. If you want to enter a category that’s crowded on iOS 6, and you’re one of the few that exclusively targets iOS 7, your app can look better, work better, and be faster and cheaper to develop than most competing apps.

This big of an opportunity doesn’t come often — we’re lucky to see one every 3–5 years. Anyone can march right into an established category with a huge advantage if they have the audacity to be exclusively modern.

I’ll be invading one as soon as I can. Here’s hoping I’m right.