From what I understand (someone like GeorgeK please correct me if wrong) the registry will have the ability to charge whatever they want for renewals since I believe the cost will soon be open-ended.
i.e. the registry can impose a renewal based on whatever criteria they want, such as a sites traffic, typeins, size, links, ecommerce, repute, etc so you could see renewal fees of 100s or 1000s of dollars a year, for example, maybe even tens of 1000s a year for large sites and valuable domains.