eMarketer has significantly revised its estimates of wearable usage downward for the entire forecast period, due to the Apple Watch’s failure to generate mass appeal. By 2020, only around on in five US adults—54.9 million—will use a wearable device on a monthly basis.

And most aren’t very likely to purchase one soon.

For marketers, the wearables user base is intriguing but not truly viable yet. “Marketers are interested in innovative wearables-based campaigns as well as basic notifications,” said Nicole Perrin, author of a new eMarketer report on wearables. “But they don’t see the technology in place yet to unlock wearables’ full potential for brands.”

Subscribers to eMarketer PRO can access the report here: Wearables 2017: The Wrist-Worn Revolution Fails to Materialize.

Listen to analyst Perrin discuss the current state of wearables usage and adoption in a recent episode of “Behind the Numbers.”

According to October 2016 polling by AYTM Market Research, less than one-third of US adult internet users said they were at least somewhat likely to buy a wearable device in the next year, while nearly half said they were at least somewhat unlikely to do so.

August 2016 polling from IAB and Maru/Matchbox found similar levels of purchase interest in specific wearable devices: 32% of US internet users who were aware of health trackers but did not already own one reported being at least somewhat interested in getting one, while 27% of those who did not own a smart watch wanted one. Awareness of both devices was over 90%.

Awareness of smart glasses and VR headsets was lower, but purchase interest among the aware population was similar to that for smart watches and health trackers.

Getting wearables onto consumers’ bodies to begin with has been a challenge.

Once that happens, there’s the ongoing challenge of making sure users keep wearing them.

For devices that still don’t have a compelling use case for most people, and that typically need to be charged frequently, there’s a worry that abandonment is a major factor.

According to the IAB/Maru/VCR&C survey, most US internet users who own health trackers, smart watches, smart glasses or VR headsets do use these devices on a daily basis. Among health tracker users, a majority said they are “always on,” with 43% of smart watch owners reporting the same.

Respondents were also syncing these devices with their smartphone, tablet or computer frequently: 68% of smart watch owners did so at least once a day, along with 64% of wearable health tracker owners, 54% of smart glasses owners and 46% of VR headset owners.

Barron’s reported in January 2017 that nearly three-quarters of Fitbits purchased in 2015 were still in active use at the end of 2016, according to Fitbit CEO James Park.