Well, we have seen several instances in history whereby a law got changed by Parliament, before the old law got put into effect. It happened later on in Denmark, when in 1953 the Salic law got abolished: the constitutional amendment to permit female succession was made retroactive, thereby displacing Prince Knud and his sons in the line to the throne.

As it was, Luxembourg has changed its laws several times, not just in the 1907 Family Statute (which abrogated the Nassau Family Pact). Consider how Grand Duke Jean in 1967 granted consent to his brother's marriage to a commoner.

More recently, a 2011 act by Parliament made the succession law fully cognatic -- applicable only to the descendants of the present grand duke. So it had the retroactive effect of displacing Prince Sebastian in the line to the throne, but not giving any places to the nieces or sisters of Henri. They would have to wait until the last male-line descendant of Princess Sophie (who married into the royal house of Saxony) died.

But then: unless one is the heir, does he really have any chance at all of succeeding? I hardly think it matters, one way or the other, whether the other female members of the grand ducal house had places in line to the throne, just as it really doesn't matter that Princess Alexandra got inserted into the succession ahead of her younger brother.