In actuality it might be better categorized as a "dance piece," but by the binary nature of the Tony categories, it's without question a Musical. We live in a world where Oh, Hello was deemed a Play and Movin' Out was deemed a Musical.
It has a story, music and lyrics; It has a live band and vocalists (so, not a CONTACT situation); It has choreography and design elements; It has live performers (dancers and singers)
The Musical race could use a shakeup, at least where nominations are concerned.
10 weeks on Broadway would be tough, financially, but as others have said if the plan is to tour it (and if Broadway is part of the tour capitalization) or film it, then a move makes sense. The only question is whether there's enough of an audience for a quick transfer, similar to SIDNEY BRUSTEIN last year.