In the latest version of the SDK for Samsung’s MultiWindow feature, it reads, “This version has been released with Android N(7.0) compatibility,” thus confirming that Android N will be known as Android 7.0. At the moment what “N” stands for is anyone’s guess, but last we checked it seemed that Google was polling users for potential names.
Now we know that version 7.0 seemed obvious given that Android Marshmallow is version 6.0, and Lollipop was 5.0. However there is precedent in which Google did not skip a full version, like with Android 4.4 KitKat where Android 4.0 was Ice Cream Sandwich. Not to mention there have been rumors that suggests that Android N could be version 6.1.
In any case take it with a grain of salt for now as for all we know, Samsung could simply be speculating like the rest of us.