ICANN has been working for several years now to expand the top-level namespace. Of course, the top-level namespace has been expanding, albeit slowly, for some time. We have new, highly specialized TLDs such as .aero, .travel and .museum; as well as more generic TLDs such as .biz and .info. We even have a set of internationalized top-level domains. But ICANN's proposal would open the top-level namespace to just about anyone who can demonstrate the ability to manage a TLD and with the money for the application.
But now, somewhat at the eleventh hour, various interest groups have announced their strenuous opposition to the expansion, in the name of copyright protection.
Milton Mueller, in this op-ed piece in CircleID, argues that ICANN "must not back down," and I agree. The central argument the copyright holders seem to have against the expansion of the namespace is that their copyrights will be more difficult and more expensive to protect with more TLDs.