There was a wealth of new tools and tricks on offer from Apple during today's Worldwide Developer Conference. But the biggest news was that Apple decided to open up a number of core services — Maps, Siri, and iMessage — that for a long time have been closed off. Given its massive install base and the billions of dollars flowing through its App Store, developers are almost certainly going to experiment with building new experiences for these areas, or at least connecting old ones. For Apple there is a huge opportunity to build big new businesses around Siri and iMessage as platforms in their own right. There is also the danger that companies like Google, Facebook, and Amazon will be able to get their hooks deep into some of the most fundamental functions of Apple's operating systems.

Let's start with Siri, since the move to open up that feature was widely rumored beforehand. Apple introduced Siri five years ago, and at the time it stood head and shoulders above anything else on the market. Since then, Apple has largely squandered that lead. Siri isn't as good at understanding queries as digital assistants from other companies, both big and small. And she doesn't have nearly the skill set of an open platform like Amazon's Echo, which has integrated with over 1,000 third-party services since its launch last year.

Siri is some of Apple's most valuable real estate

What Siri does have is the world's most valuable real estate. As of today, it's baked right into the five key categories of Apple hardware: phones, smartwatches, tablets, laptops, and TVs. Android may have the biggest share of the mobile market, but Apple customers spend far more. If you can offer a more simple transaction through Siri than you can through your own app — say, ordering a car, buying a movie ticket, or making a restaurant reservation — then making sure that voice command integration works will be a top priority.

Maps is another rich vein for developers to mine. It is used more often than Google Maps, the previous default, among iPhone owners. And location queries are often flush with purchasing intent, with people looking for a place to grab coffee, a bite to eat, or a ride to their next destination. Allowing third-party apps to surface data about places of interest or transit conditions could help Apple to catch up with Google, despite its nearly decade-long head start.

Reminder. Stickers is big business. https://t.co/14igXgc7B6 — Ben Bajarin (@BenBajarin) June 13, 2016

iMessage showed off a lot of playful new features that drew comparisons to Snapchat, and that is certainly an important part of what changed about Apple's messaging product today. But Apple really only refreshes this software once a year. If interesting and continuous changes are coming to iMessage, it will be driven by third-party apps, which can now be integrated into this feature. The best comparison here might Asian apps like Line and Kakao Talk, which have made messaging into a platform that users use to do everything from chatting, gaming, and shopping.

Next come the chatbots, and they have something to sell

So far iMessage is sticking mostly to communication, but allowing third-party apps to introduce their own GIFs, stickers, and emoji to iMessage could be a huge business all on its own. They represent an opportunity for quick, casual commerce that you can complete with just a lingering press of your thumb. And it probably won't be long before Apple starts letting more complicated transactions happen inside iMessage, as much as Facebook is positioning its Messenger app as a hub for chatbots from businesses of all shapes and sizes.

iMessage apps. Siri Apps. Maps apps. Dialler aps. Aple is opening up a whole lot more hooks for Google/Facebook/Amazon — Benedict Evans (@BenedictEvans) June 13, 2016

The big danger one could highlight for Apple, of course, is that some of these third-party apps might colonize these core functions, drawing people out of Apple's ecosystem even as they rely on Apple's hardware. Google has already taken over nearly every core function of my iPhone. If I prefer Snapchat's face filters to Apple's invisible ink, who gets to keep the ad money earned from branded filters posted as iMessages? If I reserve a restaurant through Yelp inside Apple maps, who gets the finder's fee?

Can Apple profit from letting outsiders in?

But Apple's philosophy on the value of controlling these core functions has clearly shifted. In a big change that went unmentioned at WWDC, Apple will now let you uninstall many of the stock apps it preloads on the iPhone. It's a calculated risk by Cupertino. If it can find a way to tax the transactions that happen through Siri, Maps, and iMessage as effectively as it has the original App Store, the success of competitors could keep Apple laughing all the way to the bank.

WWDC 2016: iMessage Apps