There is an interesting article on (of all places) a site focused on Disney and Disney-related theme parks that asks the question Will Disney Stop Publishing Marvel Comic Books? We all know that one of the basic rules of journalism is that if your headline asks a yes/no question, the answer is typically no.
The thing is that this headline asks a pretty valid question that once would have been a resounding "no," but with the state of the comics market, and the fact that Marvel Comics has been bleeding readers for a while now, I don't know that it is that simple of a question any more. Neither Marvel Comics nor DC Comics are the powerhouses of the comics market that they were 30 or 40 years ago. In fact, the comics market itself has never really recovered from the market's speculator-lead bust of the 90s. Sales of DC Comics are up from what they were a few years ago (thanks mostly to the bump in sales that came about due to the Rebirth initiative that the company started about a year ago), but across the industry the sales numbers are no where near sustainable in the long term.