I think the possibility that the Nissan-badged entry car in the USA could be based on this car:

Renault Modus



Why? Because the Modus--unlike the March--has already passed the European New Car Assessment Programme (EuroNCAP) safety tests, which are very similar to the tests done by the Insurance Institute for Highway Safety (IIHS) for offset frontal and side-impact testing; EuroNCAP crash tests are far more severe than the NHTSA crash tests.

Besides, from what I've read the Modus has very good interior space, very important to accommodate American-sized passengers. It's very possible that the drivetrain used on the Nissan March/Micra could fit in the Modus, so a US-market version of the Modus could use a Nissan engine with five-speed manual or CVT automatic.