It might take SCOTUS to clarify the exception, but lower courts can, and likely will, throw out evidence gathered in what the presiding judge considers a violation of the intent of the exception; and proceeds from that evidence, under the "fruit of the poison tree" doctrine.
Historically, the US (as part of its UK-derived common-law model) has let the courts refine the scope of exceptions such as "extenuating circumstances". It's very difficult to define these things in a productive way in legislation.
And, of course, there already exists substantial precedent regarding extenuating circumstances for other police activities that normally require warrants. It's not like this is a procedural vacuum.