There has been some rumors of a Scuba MB off and on for some time. The BSA is now operating it's own forum for BSA members (you need a membership number to gain access) to discuss scouting issues and there has not been anything posted on the scuba forum, the merit badge forum, or several other of the more active boards for that matter.
Having thought about the pro and con of a Scuba MB for some time I'm not sure if it would be a step forward or a step backward. If we compare, say, first aid merit badge to a first aid course it becomes quickly apparent that first aid MB is a great MB, but completing it does not make you qualified to do anything. With that as an analogy I think the point could be argued that Scuba BSA as an award is actually more prestigious than if it were a merit badge because most scouts earn the award while completing their open water certification course which means they are now a certified diver, not just someone who got their feet wet with a merit badge subject which is the more common case with most subjects.