There has been a new Notice of Proposed Rule Making ( NOPRM) application by the U.S. Customs and Border Protection (CBP). They want to put in place a non-compliant traveler fee for [my take: returning HG/PG pilots, (really everyone), that had their passport stolen when they past out drunk during a vacation out of country.]
If they open the NOPRM for public comment and should it go through as written you can expect to pay a non-compliant traveler fee if you try to reenter the U.S. without a passport or a Western Hemisphere Travel Initiative-approved document.(WHTI)
On April 14, 2016 the CBP applied to the Office of Information and Regulatory Affairs of the White House. It is scheduled to be considered this month of May.
Keep and eye out for if and when they open a public comment period in the form of a NOPRM.
If you think implanting a chip under your skin somewhere would be a better idea that should be one comment that will be passed along.
I haven't been able to confirm this El Paso Times article by Lorena Figueroa published in the Las Cruces Sun News, page 6A on Saturday, April 23, 2016.
I can't find any mention of the proposed NOPRM at the suggested website to date:
http://www.travel.state.gov