Unfortunately, Northville is going to violate several of those six elements.
a. The event is not called or promoted as a national high school championship;
NXN calls itself the national high school championship.
b. Qualification is not based on performances in the high school season or MHSAA tournament results;
Qualification for NXN is partially based on performances in the high school season. At-large spots are determined by head-to-head matchups during the high school season.
c. The event is open to all non-school teams or individuals who qualify directly through one or more non-school events, or the event is without qualifying standards and is open to any individual who pays the entry fee;
NXN fails this prong as well, non-school teams cannot qualify directly. Only teams of individuals from the same school, and therefor "school teams" can qualify for NXN.
d. If a team event, teams are not to be made up of students from a single MHSAA member school;
Northville violates this, although could get around it by adding an 8th member from a different school and not running them. NXN allowing that would also then reach compliance with prong c, although there would be a strong case that adding a non-running alternate does not put them in compliance.
e. Teams and individuals do not represent an MHSAA member school;
NXN is not in compliance here either. By only allowing teams to be made up of individuals from the same school, the teams represent an MHSAA member school. Whether they call themselves something else or wear blank uniforms, they still represent their school if no one else is permitted to run on the team.
and
f. No MHSAA member school uniforms, transportation, funds or coaches are involved.
NXN is in compliance here, with a wink and a nudge.
You can wiggle around several sections of that rule, but you cannot avoid "a". NXN explicitly calls itself the national championship for high school XC. There's no way around that. The rule is ridiculous and pathetic in purpose, but Northville will clearly violate it six ways from Sunday if they go to NXN.