Aquaman...

That's not to say that the DCEU has failed in each movie. Man of Steel has some problems but I liked it for the most part. BvS and Suicide Squad I would consider a failure (Green Lantern too if we are counting it). Justice League had problems, but did make it's money back. Although it did nothing to shake off the feeling that the DCEU is failing. WW was obviously a win.

I said using the simple metric of using double the budget. 160m budget means at 320m would be the break even point. $400m would mean that the movie would've make $40m over break even.  There is more going on than this simple metric. Such as in foreign markets like China gets more than 50%, but i was going simple. There are ancillary costs and revenue that this doesn't take into account. Such as Marketing Budget, Distribution Cost, Insurance Cost, Merchandising Cost, Home entertainment production cost etc. On the flip side Merchandising Revenue, Home Entertainment Revenue, Marketing Partnership (think product placement and product movie tie-ins), State and Federal Grants, etc. As these costs and revenues basically cancel each other out so the double metric works still for most people.

Ok then to prove that it will lose money at 400m then you will need to show first proof that it's production budget is 160m that's just an estimate. Then you need to know what it's marketing budget is. Studios never release the actual marketing budget. You will need to show proof the reshoots budget. Then you will need to show how much money companies paid to put their products into the movie. Also how much money companies cover the cost of ads in deals to market their products in commercials along with footage for from the movie. You'll need to show how much money was spent in Australia specifically, on what they spent it on,  as Australia gives a 16.5 rebate on all money spent there for movie productions if they qualify. It also shot in Morocco they have a 20% rebate on all money spent if it fits certain qualifications. We'll need to see how long they were there. How much money they spent on actual production there. To see how much money they saved. They filmed in Canada too will need to well need to see if they qualify again will need to know how long they filmed there, how much they spent specifically and on what in Canada to qualify for the 25% tax credit. Will need to know exactly what the percentage each theater takes of ticket sales in each territory. We have estimates for places like China but we don't know for sure. For each territory we will need to find out if they have a sliding scale deal with the distributors. It's less common now but the Distributor used to get more of the ticket revenue in the first few weeks. That figure varies according to the usual supply and demand principles — an extremely hot first-run movie may start out with distribution fees up to 90 percent (in other words, 90 percent of the fees during that time are going back to the studio). As the film stays in distribution longer, the fees go down since demand goes down until eventually the theater replaces it with a different film. So we will need to know if the distributor still does this and each deal with each foreign market. We will need to know the Distribution cost to the Studio too. If the theaters are digital and approved by the company to receive the movie digitally there is little cost to the distributor, but if not there is more cost. Also there are cost that we only estimated like:The industry feels that the average Sales Agent commission is 19%, International Distributor commission is 27% , US Distributor commission is 30% Cinema / Movie Theatre commission is 44%. Again this is all estimation. So unless you can provide proof of your claim that 400m would be a loss goes unsubstantiated. 

So you want to use a estimated production and an estimated marketing budget that noone actually knows except the people in WB. And you don't want to estimated the revenue that comes product placement and movie tie-ins. So basically you are picking and choosing the estimates you want. And I hate to tell you but you only have 1 more step to my simple metric which makes yours simple too. If you are going to use market budget and basically guess at it's total why not guess at how much revenue for movie tie-ins and product placement?

marketing partnership/movie tie-ins and product placement  directly effects the Marketing Cost you are adding to the Production cost.

Also the Marketing Budget estimates fluctuates from article to article. Take BvS during the debate on how much that movie needed to make to break even. Articles and People arguing about it varied the Market Budget from 100m to 250m.