Fr. Hudgins of St. Ireneaus Ministries ponders that it very well could be the Letter to the Ephesians. None of the original manuscripts of this Epistle have “Ephesians” mentioned. Only later redactions include them.
But if, indeed, there was an Epistle to the Laodiceans, that does not necessarily mean that it was an inspired work of the Holy Spirit. It could turn up today and the Church wouldn’t reconsider the Canon of the NT.