What is bPay's business model?

When Google first launched Google Wallet, they allowed users to link to it any card of their choice. I explained why that approach was not sustainable long-term. 

I have a deja vu now with Barclays' bPay: they allow for bPay account to be topped up using any UK card. 

I do understand that Barclays are using their own acquiring arm for those top-up payments, i.e. there is almost zero internal cost from that perspective. However, I was told that the bank has internal Chinese walls which would keep acquiring business unit "away" from bPay one, from accounting point of view. Hence, the acquiring cost is there.

Also, with the interchange fees set at 0.2%, Barclays would need a very high volume of transactions to see any tangible profit from bPay. (On a related note, I am not sure Apple Pay is going to get 0.15% in Europe...)

So, could anyone here at Finextra help me with an answer to the following question: what is bPay's business model? Just trying to lure customers away from Apple/Google/Samsung Pay, for the sake of it? The interchange fee? Or something else?

"Please, help!"