The mystery that surrounds Salesforce's pending acquisition of Tableau -- the still-to-be-determined parts of the deal -- is what the purchase will mean for existing Tableau users.

The $15.7 billion deal, revealed on June 10, appears to be positive for both vendors. And investors responded accordingly, with the stock price of Tableau skyrocketing on Monday and Salesforce's showing a slight gain at the start of the week.

The formerly independent BI and analytics software vendor stands to gain stability with its integration into the much larger Salesforce, while the customer relationship management giant will strengthen its position against its chief competitors by adding Tableau's platform. The acquisition came just days after Google reached an agreement to acquire Looker.

What the combination of the companies will ultimately mean for current Tableau users, however, is still speculation. Salesforce declined to comment for this story.

"That's a tough question to answer," said Rick Sherman, founder and managing partner at Athena IT Solutions, which works with various BI platforms.

"During the last wave of acquisitions, SAP engulfed BusinessObjects, which was great for SAP, but bad for BusinessObjects. So, it's to be determined," he continued. "I'm hoping they keep Tableau more independent. So far, Salesforce acquisitions seem to become more Salesforce, but most customers have both [Salesforce and Tableau software]."

Meanwhile, Wayne Eckerson, president of The Eckerson Group, a consultant and analyst who advises organizations about analytics platforms, including Tableau, said, in the near term, he doesn't expect Tableau users to notice a difference. But that could change over time, he added.

"These blockbuster acquisitions -- especially when an applications company acquires a BI company -- usually slow down innovation for the BI company, as it focuses more on integrating with the app vendor's stack," he said.

That raises another question related to the acquisition.

The Seattle vendor is known for being an innovator in data visualization. Once it gets enveloped by San Francisco-based Salesforce, Tableau is expected to continue to innovate, but its pace of product development could be slowed by its role as part of a larger whole.

"They will absolutely keep innovating," said Tim Crawford, CIO strategic adviser at AVOA, a consulting firm that advises businesses on their technological needs. "If anything, the power of Salesforce gives Tableau the resources to innovate faster and gives it greater resources to do what they may not have been able to do in the past."

Sherman was similarly optimistic, but also expressed caution.

The power of Salesforce gives Tableau the resources to innovate faster and gives it greater resources to do what they may not have been able to do in the past. Tim CrawfordCIO strategic adviser, AVOA

"They'll keep innovating; the question is how much, and that often depends on internal politics," he said. "In the short term, it will have little impact. But Salesforce is an innovator, so it's not like Tableau is going to a legacy mega-vendor. Salesforce is still in growth mode, so Salesforce is a good company for them to be with to continue to innovate."

Another potential worry for Tableau users is whether they can expect to get the same level of service from Tableau they have been familiar with. Another potential concern is Tableau's BI platform still caters to many users running its platform on premises, rather than on the cloud, while Salesforce is a native cloud vendor.

When asked whether Tableau users should be worried about a decline in customer service, Crawford replied, "No, in this particular case."

Regarding the potential complications Tableau customers used to an on-premises product may face, Eckerson said Tableau was already headed toward the cloud.

He noted that Tableau Online is already an established technology, and Tableau was in the process of expanding its cloud offerings before it agreed to partner with Salesforce.

"[Tableau] has a big roadmap that will now get altered to some degree," Eckerson said. "Of course, the upside is that Salesforce has a huge installed base, so more accounts for Tableau to play in."

Salesforce's agreement to buy Tableau in an all-stock transaction was Salesforce's biggest-ever acquisition. The deal is expected to close during Salesforce's third fiscal quarter, which ends on Oct. 31. The estimated closing date is Oct. 1.