Alongside the initial fine, Google is potentially faced with additional penalties.
If it doesn't change the conduct, as required by the EU, within 90 days, the company could face charges of up to 5 percent of the average daily worldwide revenue of Alphabet, Google's parent company, despite its appeal.
Google will get to decide how it changes its practices to comply with the EU's decision and those changes will then be evaluated for compliance. That process can take years: The EU is still deciding whether changes Google made after last year's $2.7 billion fine over the company's comparison shopping service are adequate.
The biggest potential risk for Google is to its advertising model. Google's ad business is growing much faster on mobile than desktop and, by bundling its apps together, the company has more real estate to sells its ads and more opportunities to ingest data.
"Worst case is that they'll be making less revenue from mobile," said Matthew Newman, an antitrust correspondent at MLex, a market insight firm. "Right now, it's extraordinarily hard to quantify what that could look like, since we don't know how phone makers are going to react."
For example, phone makers could still choose to voluntarily pre-install Google apps, despite this ruling. In its blog post, Google said that a typical Android phone comes pre-loaded with "as many as 40 apps from multiple developers." Alternatively, manufacturers could auction off specific app categories to app makers.
While some app makers have cheered this potential outcome, because it could theoretically level the playing field, skeptics say that the decision might be too little, too late.
Consumers in the EU may already be too entrenched in Google services to start using other apps, even if Google's options are not pre-installed.
"The consumer is likely to just simply download the apps for Google’s services if and when they get new Android phones," analysts from Credit Suisse wrote in a note to investors, "Much as they already do when they get new iPhones."
Analysts for Raymond James wrote that they expected "losses to be minimal" to Google's search revenues in Europe if it has to unbundle its apps, because the search engine has more than a 90 percent marketshare there.
Alphabet's stock dipped less than a percent in pre-market trading after the announcement and was trading slightly higher than the previous day's close by Wednesday afternoon.