They were purchased by Virgin Atlantic et al. last year and are rebranding as Virgin Connect this year. They offer a lot of regional flight destinations that AF/KL don't, especially in the UK and Ireland. If you're stateside and looking to get to these smaller cities and/or destinations being able to route through LHR/LGW/MAN and onward would now be an option with this new codeshare.

Think Isle of Man, Knock, Inverness, Jersey, Nottingham, etc. Some of the destinations Flybe flies to Amsterdam and Paris but not London or Manchester.

According to the report, Delta's looking to add their code into flights to both the UK and the EU. So you could presumably fly through CDG/AMS to a random destination in the UK that neither AF/KL fly.

While I doubt this will help Delta the airline, I imagine this will help Delta the company. Delta owns half of Virgin Atlantic, who now owns Flybe. BE's been struggling, so anything to fill their planes and make money helps Delta the company, even if the airline doesn't see much from it.