There are different ways to structure the profitability case. As you already know, profitability is equal to revenues - costs.
There are 3 typical ways on how you can structure the revenues and segment them:
1. by customers,
2. by products
3. by geographical markets
Regarding the costs you may structure them either in the fixed and variable cost, or may also structure them by different kinds of cost - like personell cost, material cost, etc. The other way to look about it is to structure the cost along value chain.
So, depending on the case you might use different approaches and segment your revenues and cost side.
Recently I've uploaded a profitability case “Deep Water rescue” (available in English & German) here on Preplounge:
I used similar cases when I was interviewing candidates on my own in Central Europe (Germany & DACH Region), Eastern Europe (Ukraine & Russia) as well as Middle East (Dubai, KSA, Lebanon, and Qatar). So, this case is very advanced and could be typically used in the 2nd or 3rd interview rounds by the leading consulting firms.
Try, whether you can crack it.