Except as specifically provided in the trust instrument, the will, or in this article, this article shall apply to any receipt or expense received or incurred on or after its effective date by any trust or decedent's estate established before, on or after its effective date and whether the asset involved was acquired by the trustee before, on or after its effective date, except that this article shall not apply to a trust while any current beneficiary is interested in a unitrust amount pursuant to subparagraph 11-2.4(b)(1); but it does apply with respect to assets to which such a unitrust may become entitled but prior to their actual receipt into the unitrust.