Now that Verizon (VZ)  has finally renegotiated its purchase of Yahoo!'s core assets, hacking $350 million off its initial purchase price, the real challenge begins.  

Verizon is aiming to generate $20 billion in 2020 sales from the mobile media unit that draws on Yahoo, AOL and its other digital properties. The telecom still needs approval from shareholders and regulators, but expects to close the deal in the second quarter and tackle its outsized growth targets. 

"That's a tall order," said Roger Entner of telecom consultancy Recon Analytics of the $20 billion goal. The size of Verizon's target base requires content that would play across multiple continents. Facebook (FB) and Alphabet's (GOOGL) Google benefit because users provide content and searches that drive advertising. "You need a lot of inventory in a lot of different languages," Entner said. 

Whether the telecom gets there by growing its existing businesses or by making more acquisitions, it has a long way to go. The telecom will be hard-pressed to meet its goal and may have to borrow from the playbook of rival telecom AT&T (T)  and be more aggressive in the M&A sphere. 

Verizon reported that its fourth-quarter digital media revenues came to $532 million, but did not reveal full-year results for the digital media properties. Researcher eMarketer put global digital ad sales for AOL and Verizon's other digital properties at $1.56 billion in 2017 net of payments to partners that drive traffic to Verizon's sites.

For its part, Yahoo is on track for just under $3.5 billion in total sales in 2017, according to the analyst consensus compiled by FactSet, while eMarketer puts digital ad sales net of traffic acquisition costs of $3 billion. To hit its 2020 goal, then, Verizon would have to roughly quadruple sales from Yahoo and its own digital portfolio, absent any other acquisitions.

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Google and Facebook dominate the eMarketer listings, with projected net digital ad sales of nearly $74 billion and $34 billion, respectively, for 2017, after subtracting amounts paid to partners to acquire traffic. Together, the two account for more than 45% of the worldwide market.

Meantime, Verizon's digital media unit and Yahoo account for just 0.6% and 1.3%, respectively, of the projected 2017 market for global digital ad sales, suggesting that the companies at least have room to grow. While he didn't name Google and Facebook specifically, Verizon CEO Lowell McAdams said in mid-2016 after the initial Yahoo purchase agreement  that advertisers are "hungry for alternatives as the market expands for both in-home and mobile consumption," and suggested that the telecom would seize a bigger role.

In particular, sports is a niche where Verizon and Yahoo could expand.

Professional sports are getting more attention with current reports that Facebook is exploring a streaming deal with Major League Baseball, and Twitter's (TWTR) Thursday Night Football streaming pact from 2016.

"A lot of people forget that Yahoo was really a pioneer when it comes to Internet live streaming of sports," said CFRA Research Analyst Scott Kessler. The 2015 showdown between the Buffalo Bills and Jacksonville Jaguars in London may have been forgettable, but Yahoo's NFL deal pre-dated Twitter's streaming agreement last year. 

"Could Verizon with Yahoo come to more agreements on that front? Sure," Kessler said, noting that Verizon itself has mobile streaming agreements with the National Football League and National Basketball Association.

"Twitter has made [live streaming sports] a centerpiece of their growth strategy," he said. "They have spent a lot of time, money and resources to put together these deals."

Twitter also has a pact with Bloomberg to stream financial content. Finance is another focus of Yahoo's, suggesting that Verizon and Twitter could increasingly bump up against each other as they both try to claw advertising revenues away from Google and Facebook. 

For its part, AT&T has made a more ambitious and costly push into video by acquiring DirecTV and moving to acquire Time Warner (TWX) . Since acquiring DirecTV, AT&T has launched the DirecTV Now service that streams cable channels to subscribers for $35 per month, advancing its mobile video efforts.

But Verizon has preferred smaller digital content deals to massive buyouts of legacy media properties. 

After Verizon announced an unlimited wireless plan earlier in February, Macquarie analyst Amy Yong Dish suggested in a report that a need for wireless capacity could push the telecom to buy Dish Network (DISH) or its wireless spectrum licenses. Acquiring the satellite TV company would give Verizon Dish's Sling TV, a $20 per month competitor to AT&T's DirecTV Now.

Buying a company like Dish, with a $29 billion market cap, would mark an abrupt change to Verizon's video strategy. Adding Dish's streaming service and its negotiating experience with cable networks and other content providers could help it reach $20 billion by 2020, however. That kind of ambition doesn't come cheap.

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