According to a post by Lighthouse on the Official City of Heroes forums the people at NCSoft have heard your requests for more character slots, undoubtedly spurred by the Powerset Proliferation and Villain Epic Archetypes to come in Issue 12. Their plan? To give you more character slots as you requested! They intend to have this system in place shortly after Issue 12 goes live. The character slots will not be free but will cost a as of yet undetermined fee.
You can find the original post here.