Well they better announce a deal in less than 24 hours, because if they don't any means to pass a bill will definitely take longer than the 17th. By that time, the chain reaction for a economic collapse might be already brewing. From what I read, there's a few tricks the U.S Treasury can try to avert default for at least a month after the debt ceiling is reached. But even with that, America's credit rating will still crash (read downgrade to oblivion the longer it goes on).
