During Tuesday's Disney earnings call, it was announced that the company's streaming service -- Disney+ -- is now at 28.6 million paid subscribers (a figure that may not even include the consumers getting the service for free via a deal with Verizon).

That number is some incredible growth since the service launched in November 2019. But now comes the hard part: keeping the increase going as the novelty of the service wears off.

CEO Bob Iger completely understands this challenge, and was sure to address Disney+'s biggest releases for 2020: The Mandalorian (season 2) will arrive in October after a breakout first season, and the plan is to do more seasons and potential spin-offs thereafter. Marvel's first original Disney+ series, The Falcon and the Winter Soldier, is slated to arrive in August. The second, WandaVision, will appear on the service in December following an early January announcement that the show would move up from a previous 2021 release date.

Iger's notes come on the heels of three big Super Bowl spots for Disney -- Marvel's Black Widow, Disney's live-action Mulan and a specific-to-Disney+ teaser for The Falcon and the Winter Soldier, WandaVision and Loki (due 2021); all three based on existing intellectual property. He also noted that there are seven other Marvel shows in some form of development right now. We already know a bunch of those (Ms. Marvel, She-Hulk, Moon Knight, What If..., Hawkeye), but the two additional titles remain a mystery. They're also crucial to the continued subscriber uptick for Disney+.

Because at the moment, Disney+'s success hinges entirely on existing IP, and its ability to draw audiences in. That was kind of the point from the start, as the service was uniquely positioned to succeed early because it had more known entities than its competitors. But the ability to watch your childhood favorite shows or movies only buoys a service for so long. Churn remains an issue for Disney+ and every service -- especially if you're not providing new content at a clip that's fast enough to stop them from unsubscribing.

That fear is part of why Disney has and will continue to lean so heavily on existing IP, too. Something you'll certainly notice just from a quick skim of this list of upcoming Disney+ original programming and projects in development? Nearly all of it is a spin-off or sequel of some sort.

Generating unique hits as Netflix has with Stranger Things, House of Cards and others is no easy feat, and for each of those successes are plenty of failures along the way, too. At this stage in the game, Disney+ doesn't want to deal with a ton of failure. It has the cash on hand to do so, sure. But as the streaming wars wage on in 2020, there's a finite amount of time to hold audience attention. "Too much" content may already be a thing, and it's just going to get harder to stand out compared to the numerous other subscription services out there. So the known quantity could now not only be the safest bet, but the only one in a battle for differentiation.

What will be interesting to watch for Disney+ is how the subscriber numbers grow compared to the release of the new Marvel shows, in particular. While Star Wars fans were satiated by Disney+ right away with The Mandalorian, Marvel fans' most enticing offer has been most of the Marvel Cinematic Universe's films, 90s cartoons and bonus footage from last year's blockbuster Avengers: Endgame. There's still nothing new slated 'til August, yet fans are still chomping at the bit. According to always-on TV ad measurement and attribution company iSpot.tv, the Marvel Disney+ teaser garnered the fourth-highest digital share of voice of any Super Bowl spot on game day. It's not the only way to measure hype around shows, but it's an indicator the demand is high. Subscriptions may even be on hold until those shows arrive.

The good part of leaning on existing IP for any entertainment entity is that it does some of the marketing work for you, since the fan base is built in. Disney+ has a major advantage there, and the fact that they'll continue to exploit it should come as no surprise (and as discussed, they're largely obligated to do so). Still, you can only reheat IP successfully so many times, too.

After success after success at the box office over the decades, Solo: A Star Wars Story didn't even make it to $400 million at the box office in 2018. Long-time fans were equally mixed on the final chapter of the original nine-movie arc, The Rise of Skywalker (though it still did just fine at the box office, topping $1 billion). Marvel wrapped up the "Infinity Saga" last year, and now must move on without core characters like Captain America and Iron Man, and at least at current, there is no unifying theme. They'll also perhaps take their biggest risk to-date in the MCU with November's Eternals release. Disney+ shows will start coming at clips of three or four releases per year, and figure to feature increasingly obscure characters for a non-superfan audience. Is there a limit to how high that rocketship can go, too?

It may take years to find out one way or the other, but we will. In the meantime, Disney is happy to give you what you know and love, because you know and love it. That'll be enough -- until, maybe one day, it isn't.