A lot of discussion has already taken place on the role of a trusted third party in an NFC business model. The creation of such an entity means that a regulatory body should be assigned to manage the TSMs per country or zone. Typically, each country would have at least one TSM.
I argue that the MNO should take over the role of the TSM.
The MNO already has a CallCenter which can be used for the new service support.
With the Secure Element (SE) on the MNO SIMs, ( which looks like the most viable option to deploy NFC), the operator already carries out essential activities such as provisioning, SIM blocking, etc.
Mobile devices are naturally associated with the MNO as opposed to the financial institutions. The end user who is facing a problem trying to purchase using an NFC device will naturally call the MNO call center to yell the typical "I cant buy with the mobile phone"
Since the TSM, who is now the MNO needs to have access to the credit card details of the subscriber, strong partnership between the MNO and the financial institution (card issuer) is required. It therefore makes sense that the MNO and the bank operate as one entity. We can as well have the MNOs and banks merging to form a Mobile operator-cum bank. Each mobile operator-cum bank then becomes three entities in one (MNO + Bank + TSM)!
If we also look at it from another angle, we see that a subscriber who has lost the NFC device simply calls the MNO_BANK_TSM and the SIM (with all the credit cards) is disabled. This reduces any fear by the subscriber that "Maybe my cards are still active with the bank" ( well the bank is now a mobile operator!)