We may as well start with a toast to Roku (NASDAQ:ROKU) for its monster gain in 2019. The video-streaming specialist saw its shares more than quadruple -- up 337% -- last year. Investors scored a lifetime of gains in a single year, but what if the party isn't over just yet?

I recently went over some of the things that can go wrong for Roku investors in 2020. Let's take a more bullish approach and consider the things that can go right for the high-flying market darling.

ESPN streaming through the Roku operating system on a TV with a streaming box, remote, and earbuds.

Image source: Roku.

1. Streaming trends can keep improving

We're spending a lot of time steaming video in general -- and with Roku in particular. Roku has seen its audience of active accounts soar 36% over the past year to 32.3 million, but that's just one ingredient of the hot company's super sundae. The cherry on top is consumption, as the average account is spending nearly 3.5 hours a day on the platform. The 10.3 billion hours spent streaming through Roku's hub in its latest quarter represented an increase of 68%, and it's naturally great to see that metric growing even faster than the platform's audience. 

Engagement is a beautiful thing, but some may start to wonder if an average of 3.47 hours is nearing the ceiling for a company that now earns the majority of its revenue from consumption. Can active users become even more active? The good news is that the trends keep pointing in that direction, particularly with the launch of a couple of buzz-generating premium streaming services during the fourth quarter. A lot of these Roku accounts are also shared family registrations, so this is not just about a single person's viewing habits. 

2. New services can grow in popularity 

There are many components going into the perpetually rising average revenue per user that Roku is generating. It sells advertising on its hub, and it also scores ongoing referral fees when viewers sign up for new offerings through Roku. 

Roku doesn't generate a lot of money from the biggest services because most of those subscribers were already registered members. The real payday here should come from new services and the hungry upstarts that are willing to pay a lot to stand out in a crowd of what is now thousands of available apps on Roku. The future is bright on that front. There was a big one-two punch in November of high-profile launches, but the next few months will find other media giants introducing new offerings. Standing out on Roku is now an important component of any launch's promotional strategy.

3. An economic slowdown may actually help 

The largely buoyant economy has been good for most consumer-facing companies, and Roku has clearly benefited from a rise in folks feeling comfortable enough to upgrade to smart TVs or pay up for Roku-branded hardware. Something that isn't really being noted these days is that Roku is also positioned well for investors in the event of a recession

Roku's platform is free to use. It's the default operating system for a growing number of smart TV manufacturers, and even if you have to go out and buy a Roku plug-in stick or box, it will set you back as little as $30. An economic slowdown will drive even more people away from pricey diversions like going out to restaurants and the corner multiplex. Budgeting will also lead more consumers to cut the cord on their cable and satellite television plans. Roku will be there to fill the void, getting consumers up to speed on cheaper streaming TV options.