U're not sending fees anywhere. It's forger picking them as reward up, when he signs block. There're can be some options coded:
1) Forger'll get reward;
2) Every NXT get reward proportionally;
3) No reward at all.
Only first variant stimulates potential forger to forge with goal of getting profit. Ofc, stable safe "green" decentralized payment system (with features) so desirable for many people, so they probably'll forge for free, but it's up to devs to decide. Stimul + free will better than only free will as I recall.
And there's fourth:
4) Every forging NXT get reward proportionally. I suppose, p2p-pool of forgers can be implemented.