There can be laws made concerning need of bathrooms whether in number or ratio for particular events according to attendance or in public or private buildings in order to satisfy sanitation and building codes yet governments shall not decree the entry requirements for bathrooms (except their own) based on sex or gender identifications for social purposes.
Private and independent entities will determine their own bathroom assignment policies concerning binary & non-binary users or whether to have traditional or unisex or single use bathrooms, etc. Owners or their managers will determine their bathroom designations as long as relevant sanitation concerns do not arise. Law enforcement will have power to help enforce such entities' assignments and thwart trespassers.
Government buildings may within reason reserve bathroom(s) on a particular floor or location for non-binary users or implement some managed time interval or clearance routine on their behalf. Yet no frivolous and expensive bathroom additions will be made to cater to a low-threshold of gender-identity minorities and the same applies concerning laws or mandates for the general public's bathrooms.
Any type of harassment, assault or personal violation committed within any bathroom will be prosecuted whatever the bathroom admittance policy is and a declaration of a public nuisance may apply to frequent-offender establishments.