As you & Richard have mentioned, the plan is to begin offering overdrafts next year. Tom has said that overdrafts will enable Monzo to break even.
Then the next products that Monzo will focus enabling users to purchase next year will be
which will probably be delivered through Monzo’s marketplace. Tom has talked about Monzo’s approach generally being to enable customers to select the products they need from multiple providers, through that marketplace, rather than Monzo providing them directly.
This means that customers can choose the solution that’s most suitable for their needs & is best value while also removing the temptation for Monzo to offer a superior (not as profitable) product to new customers and then offering an inferior (more profitable) product to existing customers, by taking advantage of the customer’s inertia, which is the legacy banks approach.
I was watching a presentation which gives an excellent overview of marketplaces as a business model / investment proposition & the benefits for customers yesterday. It mentioned that Amazon makes ~25% gross margin from sales it makes directly to customers, whereas it makes 80%-90% gross margin from sales of goods from other merchants through it’s marketplace.
I think that gives some sense of how much more profitable the marketplace model can be.
If you want to know more about Monzo’s thinking on this topic, there’s a lot of resources that’ve been collated in this community 
this was Tom’s most recent, in depth interview -
posts with analysis of Monzo by the media all have :newspaper: in the title (just search for that). There’s more :radio: podcasts. And you can find posts from the Monzo team by searching for “group:Monzo + your search term” 