It’s official. On March 25, Apple will hold a long-anticipated event in which it details its upcoming streaming and media subscription services. It’ll arguably be the company’s most important announcement of the year.

During the presentation, Apple executives should fill in some very large blanks in its subscription ambitions. The company has already cut deals with headline talent like Oprah Winfrey, M. Night Shyamalan, and Reese Witherspoon. Its shows have already roped in talent like Chris Evans, Jennifer Garner, and Steve Carrell. And it has committed at least a billion dollars to the project, a pittance given the company’s war chest, but enough to signify the seriousness of its intent. But beyond that? No one outside Cupertino has any idea what the company’s got planned.

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“We don’t have any information. We don’t know the price point or the business model,” says Day Rayburn, a streaming media analyst with Frost & Sullivan. “Now we’re going to finally figure out what the hell Apple’s doing.”

The possibilities are broad. What shows and movies will be available at launch, and how regularly will new entries hit the library? Will it be its own product, or rolled into a larger subscription that encompasses Apple Music and Apple News as well? What demographic will it target? Will Apple make any of it free to people with iPhones and iPads and Apple TVs? Will it use its the content subscription to drive you to other Apple services, like Apple Pay?

The closest CEO Tim Cook has come to fleshing out those details was in the company’s most recent earnings call—and it wasn’t very close at all. “We will participate in the original content world,” Cook said. “We have signed a multiyear partnership with Oprah. But today, I’m not ready to extend that conversation beyond that point. We’ve hired some great people that I have a super amount of confidence in and they’re working really hard and we’ll have something to say more on that later.”

That “later” now has a date. (Which, it should be noted, BuzzFeed News first reported back in February.) But whatever details Apple gives on March 25 don’t just matter for quelling your curiosity. It also will have a significant bearing on Apple’s future, as the company increasingly looks to its services business to make up for waning iPhone revenue.

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Not that the iPhone has suddenly become unpopular. It still accounts for nearly two-thirds of Apple’s revenue. But smartphones have long since settled into commoditization. People upgrade them less frequently, as each year brings iterations and refinements rather than real breakthroughs. It’s unclear even what an iPhone breakthrough would look like, at least until Apple’s ready to experiment with a folding phone, which seems unlikely for at least the next couple of years. It’s no wonder that, in the most recent quarter, iPhone sales declined 19 percent year over year.