On Friday, owners of Alphabet (NASDAQ:GOOGL, NASDAQ:GOOG) received some important news, when GOOG announced that Google Cloud would have a new leader.

Diane Greene, who has headed Google Cloud for the last three years, announced her resignation. The company reported that it would replace her with Thomas Kurian, a longtime Oracle (NASDAQ:ORCL) executive. While Google Cloud made great strides under Greene’s direction, it remains behind the cloud units of other big tech companies. The performance of the unit under Kurian’s leadership will likely define whether it becomes a primary revenue driver for GOOG or a relatively small niche play for the company.

Google Cloud Begins a New Chapter

Greene, who came to Alphabet from VMware (NYSE:VMW) in 2015, said she will leave her CEO duties to “turn to the passions I’ve long had around mentoring and education.” She will remain a director on Alphabet’s board.

During her tenure, Greene redefined the Google Cloud brand, bringing all of the company’s enterprise efforts into the Google Cloud ecosystem. As a result, Google Cloud went from having only two major customers to attracting numerous Fortune 1000 clients.

Still, not all went smoothly during Greene’s tenure. The company’s focus on artificial intelligence enabled it to obtain a Defense Department contract related to drone targeting. However, a backlash from within the company forced Alphabet to end this contract. Also, Google Cloud remains well behind its larger peers. Though Google’s share of the market has grown, it held only a 3.3% share as of the end of 2017.

Kurian Could Make or Break Google Cloud

During Alphabet’s third quarter, its “other revenues” which includes revenue from Google Cloud, stood at $4.6 billion. Though “other revenues” rose 29% from last year’s Q3, Alphabet declined to break down how much of it came from Google Cloud. Analysts estimate that Alphabet will generate $136.5 billion of revenue in 2018, most of which comes from digital ads.

Credit Suisse forecasts that GOOGL will generate $6.9 billion of cloud revenue for all of 2018. In comparison, Amazon had $6.68 billion of cloud revenue in Q3 alone.

One analyst believes that Alphabet, in an effort to boost its cloud business, will try to outbid IBM (NYSE:IBM) for Red Hat (NYSE:RHT) to catch up to its peers in the areas of sales and support. Since GOOGL has over $106 billion of cash, it can enter a bidding war with IBM, which offered $33 billion for Red Hat.

Conversely, a partial or full surrender to AWS and Microsoft’s (NASDAQ:MSFT) Azure could occur. Either way, I think we will know sometime in 2019 whether Google Cloud will redefine the future of Alphabet, or if the money Google Cloud attracts will forever be defined as “other revenue.”

Final Thoughts on Google Cloud

In all likelihood, Kurian’s tenure will define the influence that Google Cloud will have on GOOGL stock. Greene made considerable strides towards making Google Cloud a player in the software business. However, her efforts led to controversy within the company and a relatively small market share. Kurian will have to increase Google Cloud’s share to the next level or surrender. I think investors will know quickly whether the cloud will become the future growth engine of GOOGL stock or if Alphabet will have to find another way to diversify the company away from ad revenue.

As of this writing, Will Healy did not hold a position in any of the aforementioned stocks. You can follow Will on Twitter at @HealyWriting.