Have you ever seen an in-house advertising or marketing function turned into a profit center? And if so, did it succeed or fail? I am seeking an example that shows how such an in-house function can be restructured--and maybe even given its own P&L.
The only way this could work is by outsourcing the people to other companies.
But this would change the business you're in and you might as well just outsource the department to a company who does this already.
If recommend reading a book called "The Goal" - it explains things better than me.
In a B2C scenario, I've seen this done by leveraging user acquisition to generate leads for third parties. You can monetize the registration flow by adding these partner offers and keep the difference between what it costs to acquire a user and what you can sell the leads for.
In B2B, demand generation teams have become very effective at measuring the impact of their activities in sales with the help of marketing and sales automation platforms. While the revenue typically doesn't sit on the marketing team's P&L, they are able to demonstrate that their marketing activities are profitable for the business.