As the year of Apple's (NASDAQ:AAPL) smartwatch approaches, investors and analysts are beginning to give the upcoming device more weight in their stock price targets. The estimates of exactly how well the device will sell range widely, leaving us little option but to guess about the level of demand for the Apple Watch in 2015. Maybe new commentary from Morgan Stanley's longtime Apple analyst, Katy Huberty, will help bring the sales picture into focus.

Apple Watch. Image source: Apple.

A bullish bet on Apple stock
Apple stock is headed to at least $126, or 6.5% higher than the share price at the time of this writing, Huberty predicts. This is up from her previous 12-month target of $115. Pre-split, that's $882. Most notably, $126 would give investors who bought Apple at its lows in 2013 more than a whopping 120% return.

But Huberty's projected range for Apple stock extends well beyond $126. Her bull case sees shares reaching as high as $150, up about 29% from where Apple trades today.

Key to her increased confidence in Apple stock is a bet that the Apple Watch will be successful. More specifically, she predicted (via Fortune) that Apple will sell 30 million of the devices in its first year. This would be a record initial product launch for Apple, more than doubling the 14.8 million iPads sold in its first year. Hubety's estimate for Apple Watch sales is higher than the current consensus analyst estimate for 22.6 million unit sales in 2015. 

How to think about Apple Watch potential
One of the most interesting takeaways in Huberty's note is how she arrived at her estimate for 30 million Apple Watches in its first 12 months of availability. While this figure might initially seem extraordinarily high, putting it in perspective within a percentage of Apple's user base brings the prediction down to Earth.

"We believe looking at penetration into the Apple installed base yields the most realistic assessment of demand potential of the Watch." Huberty explained. "Our 30M unit estimate implies 10% penetration into Apple's 315M iPhone 5 or newer installed base exiting 2014, which is lower than iPad penetration of 14% in its first year but higher than iPhone at 7%."

In other words, Huberty expects Apple's massive base of loyal customers will be a key driver in propelling the largest adoption of any new product the company has ever launched.

Apple Watch. Image source: Apple.

While Huberty's methodology seems sensible, we are likely still no better off than monkeys with a dartboard when it comes to predicting the device's success. Fortunately, Apple's conservative valuation means Apple shareholders won't have to play the guessing game for now. A successful launch for the Apple Watch or not, the stock looks worth holding.

Editor's note: The time frame of Huberty's estimate for 30 million Apple Watch sales has been corrected.