The comic book, that is.
Former head Sonic The Hedgehog writer Ken Penders has claimed on his message board to have successfully wrangled copyrights on many of the characters he created during his run. Penders left the series a few years ago (leaving it to new writer Ian Flynn to handle the series) under uncertain terms. If anything, as his work was presumably Work For Hire (as Archie does with most writers and artists), they just stopped hiring him. Penders appears to have gotten copyrights on characters he created during his run, such as Rob O’ The Hedge and Lara-Su. He first investigated it when parallells to his work were noticed in Sonic Chronicles: The Dark Brotherhood.
Given that the current comic (the longest-running licensed comic book) continually references characters and events from that era, if this copyright claim holds true, Archie would have to do some serious revisions to the book. Undoubtedly, though, I can’t see this ending with Archie losing the rights to the characters, and Penders continuing with his goal of writing stuff without Archie’s approval. The characters could easily be shuffled away, but the concepts have been pretty much integrated wholesale into the Sonic universe.
Or, heck, Archie could just cancel the book.