The NFL is changing the kickoff as we know it, and surprise onside kicks are now banned. Normal onside kicks are almost impossible to recover due to numerous rule changes, such that there have been attempts to invent an alternative to the onside kick in an effort to gain consecutive possessions.
One such (repeatedly shot down) idea is the 4th-and-long conversion. Here’s the Philadelphia Eagles’ failed proposal:
The Eagles’ proposal to allow teams to line up their offense on the field on fourth-and-20, instead of kicking off, was rejected today in a vote at the league meeting.