A few years ago, it seemed that wristwatches were an endangered species, thanks to cellphones effectively replacing them. A new report from Juniper Research, on the other hand, indicates that they’re coming back in the form of smart watches. The company expects more than 100 million smart watches to be in use by 2019.

Juniper outlined its findings in a report titled “Software-driven Differentiation, with no Killer Apps in Sight According to the report - Smart Watches: Market Dynamics, Vendor Strategies & Scenario Forecasts 2014-2019.”

The report cites a line of premium smartwatch introductions over the next 12-18 months. One of the biggest is the Apple (News - Alert) Watch, but it’s not only Apple, Google, Sony and LG introducing smart watches, luxury watch makers like TAG Heuer are planning on introducing their own models.

Smartwatches will embrace more diverse functionality rather than earlier phones like the Martian Notifier, which as the name suggests, focuses on notifications. Smartwatches can already run a number of applications such as GPS and games. Some can answer phone calls and text messages.

Despite their growth, smartwatches still lack a “killer app” that will convince people they have to own one. That still might be a matter of time. After all, it took two years from the Apple II’s introduction in 1977 for VisiCalc, the first computer spreadsheet, to make it into a must-have business tool. Lotus 1-2-3 took two years after the introduction of the IBM (News - Alert) PC to do the same thing.

Juniper cited Fitbit as a potential killer app, but the company still targets multiple devices.

One possible advantage is that smart watches compliment smartphones by being able to handle calls and messages while the device is safely ensconced in a pocket.

Even as they keep selling, smart watches won’t be cheap. Juniper expects them to cost over $200 until around 2020.