Last week, Facebook opened up Messenger usernames for all businesses, encouraging them to promote their Messenger presence in the same way that Facebook once encouraged brands to promote their Facebook pages.

Here are the main questions marketers need to understand about Facebook Messenger to determine just what role it will play in their marketing mix going forward:

1. Will it be all pull, or also push? Currently, Messenger operates as a mechanism for pull marketing. If you're a shoe store, a customer may message you to find out your hours or ask whether you have a certain brand and size in stock. If this store is very responsive on Messenger, then it has a chance to get the sale over a less responsive competitor.

Will Facebook ever turn this into a form of push marketing? If so, how? There are two ways that this could work. One is by allowing consumers to opt into hearing more from certain brands. In this case, Maria chats with Acme Shoes and checks a box saying Acme can reach out to her in the future. Then, when Acme gets a new shipment of shoes from her favorite brand, it could proactively send her a message via a notification through the Messenger app. Facebook should work with marketers to help businesses non-intrusively reconnect with customers who are already interacting with them.

2. How does paid media complement owned media? In the example of Acme Shoes, even if Maria opts into notifications, Acme may have to pay to message her proactively. This is what Facebook did with fan pages for brands. As brands build an audience of people who "like" them, brands still have to pay to promote posts to that audience. For now, Facebook will likely keep its Messenger offerings free so that brands integrate with its platform. If Facebook wins this land grab -- and there is no doubt it will be one of the biggest global winners here, if not the most dominant platform -- then expect paid media to play a major role.

3. Who supplies the data? When Maria first sends a message to Acme Shoes, what does Acme know about her? Can it know that she also follows Cole Haan, Gucci and Alexander Wang? Is it allowed to know her general or exact location so it can send her relevant store locations? Can it tie this into its own customer relationship management system to determine that Maria has spent $3,500 with Acme over the past six years? Marketers will want as much data as possible at their disposal in a way that's easy for their Messenger representatives to tailor their messages and measure the performance of Messenger marketing.

4. What will be manual, and what will be automated? If Acme Shoes gets hundreds or thousands of customers a day asking for store hours, it will want to automate such responses. Expect messaging follow a course that customers are used to through phone-based support. Anything that can be automated will be, and then representatives will chime in as soon as more complicated queries arise. Meanwhile, machine learning through Facebook and various third parties integrating with Messenger will keep expanding the possibilities for what can be automated. Manual responses will then be used either by small businesses that can't afford automation or by larger businesses when facing unique queries. Expect a few large businesses to declare themselves "100% robot-free" to use human-to-human service as a differentiator.

5. What will Messenger marketing replace? If Facebook Messenger wins, what loses? Call centers could field less volume, but in the short term, it may merely shift resources from representatives manning the phone to manning instant messaging.

What about mobile applications? If consumers can get support information and order products right from Messenger, will marketers still need mobile apps? Such apps are expensive to maintain and update, but they are also an important form of owned media, where marketers can send notifications to users who opt in. Such apps also offer permanent branding on customers' mobile handsets. Marketers should clamor for Facebook to provide push marketing opportunities.

Google could be a loser here, as could local businesses like Yelp. There's a whole ecosystem around local search optimization, from marketing agencies to location management offerings such as Yext. If Messenger becomes a new portal for consumers, some businesses will successfully partner with Facebook while more vulnerable ones will perish.

Should such ripple effects take place, that will free up budgets that marketers currently spend in areas such as paid search and app distribution. Could Facebook find new ways to grab those budgets by creating new sponsorship opportunities within Messenger?

That's such an easy question that you don't need a chat bot to tell you the answer.