For all its hypotheticality, I do enjoy musing who is "the right heir". Contrary to most people, I guess, I started out as a Maria Vladimirovna supporter and now find myself leaning towards Prince Nicholas Romanovich! Even though I don't take any humane considerations into account (OK, except that I do very much like that his mother was born a Countess Sheremeteva; though Italian countesses like his wife seem to be a dime a dozen) I have started to question why the Pauline Laws should apply when the dynasty isn't reigning/imperial. I think the most benevolent position is that there are no more true dynasts and they're all just Hohenzollerns and Princes Romanovsky.
BTW how lovely ironic isn't it that although no longer Russian dynasts, they all are Holstein-Gottorps (the ducal Oldenburgs had no house laws - thus several spouses were mere countesses!) and heirs of their pretender title: Наследник Норвежский - Heir to Norway! :-)