The "Pending" status is a suppressed No Result. It indicates that a result has not been received for the backup but it is within its user defined "No Result Threshold".
A backup will transition from "Pending" to "No Result" once it has exceeded the number of days defined in the "No Result Threshold".
Is this something that may/is going to replace No Results?
No it will not be replacing the No Result status.
What is its specific purpose?
It provides better visibility into backups which have not received a result but are within their user defined "No Result Threshold".
This new status provides a better gauge for actionable statuses and delays non-critical issues while still being aware that expected results are missing.
How will it be represented in Reports?
At this time it will show up as a "Warning", however in future it will be listed as "Pending"