Roku's (ROKU 1.91%) active accounts and streaming hours exploded in 2020 amid the coronavirus pandemic, and its outlook for 2021 is still strong. In Roku's first-quarter letter to shareholders, management wrote, "we expect net adds of both active accounts and streaming hours to be above pre-COVID-19 levels." Management also anticipates an uptick in streaming hours per account over 2020. 

Here are three reasons management is so confident about the company's continued growth even as more out-of-home entertainment options become available again.

A TV displaying the Roku homescreen.

Image source: Roku.

1. New streaming services

Several high-profile streaming services entered the market in late 2019 and 2020. However, Comcast's Peacock and AT&T's HBO Max didn't actually show up on Roku devices until late last year.

On top of that, Discovery launched Discovery+ at the start of this year, and a CNN+ streaming service could be in the works as well.

This summer, Peacock will stream a large amount of Olympic Games content, which could boost its popularity and draw more users to Roku devices. (As of June, Peacock still doesn't have a deal with Amazon Fire TV.)

Broadly speaking, media companies are adopting direct-to-consumer streaming and making more of their content available on connected-TV platforms. And Roku is investing in content for its Roku Channel. With more content available to stream than ever before, it should see an increase in user engagement.

2. International growth

While Roku is already the most popular connected-TV platform in the U.S., it's still in the early days of its international expansion. Management is following the same playbook in foreign markets as it did domestically: first scale its user base, then increase engagement, and then improve monetization.

So far, it's working well. In Canada -- one of the first international markets it pushed into -- it's already the No. 1 smart TV platform. In Mexico, it's No. 2, and has the top-licensed smart TV OS.

Roku has an additional advantage in international markets: Viewers in those markets are more prone to engage with ad-supported content versus subscription services. Those services are a bigger focus for Roku than they are for its competitors, and The Roku Channel gives it an additional leg up. That streaming service is currently available in Canada and the U.K., as well as the U.S.

As Roku continues to establish itself in international markets like the U.K. and Brazil, it's well-positioned for strong account growth even compared to a couple of years ago.

3. The continued shift in media consumption patterns

Roku operates under the assumption that all TV will become streaming media. That said, Americans spent an average of 3.5 hours per day watching traditional TV in 2020, according to an estimate from eMarketer. The analysts expect TV viewing to decline by 16 minutes per day this year, and about half of that time will be shifted into consuming media on connected devices and platforms like Roku's.

Two factors are driving the decline in traditional TV viewing. First is a shift among cable subscribers from watching linear TV to viewing more on-demand streaming content. Second, and more importantly, cord-cutting is on course to accelerate in 2021, and that trend is forecast to continue throughout the decade. Those trends should combine to produce a sustained shift in viewership from traditional TV to streaming programming.

Also, in 2021, U.S. audiences are likely to have less interest in news programming -- absent a raging pandemic and a presidential election -- and more interest in entertainment, which is best served via streaming. That should produce greater engagement among Roku users regardless, but when you factor in the increased number of streaming options, average engagement on Roku should still climb compared to 2020. Add in the potential for strong international growth, and 2021 should be another year of rapid growth in users and engagement for Roku.