May a juvenile convicted as an adult of a non-premeditated homicide be sentenced to life-without-parole under Offense Level 43 and bear the burden to demonstrate he is not one of the 'rarest of cases'?

QUESTIONS PRESENTED I. May the sentence of a juvenile convicted as an adult of a non-premeditated homicide constitutionally start from a guideline of life-without-parole under Offense Level 43 and then be compelled to shoulder the burden to demonstrate that he is not one of the “rarest of cases” described in Miller v. Alabama, 567 U.S. 460 (2012) and Montgomery v. Louisiana, 136 S.Ct. 718 (2016)? II. Must the Sentencing commission be required to rewrite offense level 43 as it pertains to a juvenile since a life-without-parole sentence it is no longer consistent with the pertinent provision of title 18 as that title pertains to a juvenile after Miller v. Alabama, supra, and Montgomery v. Alabama, supra?