This chapter shall become applicable on January 1, 2001, to every trust and decedent‘s estate already in existence on January 1, 2001, and to every testamentary trust to be created on or after January 1, 2001, from a decedent’s estate that is already in existence on January 1, 2001; provided, however, at any time prior to January 1, 2003, any such pre-existing trust or decedent’s estate (or testamentary trust to be created from a pre-existing estate) shall have the right to elect to continue operating under the law in effect prior to this chapter. Any fiduciary, income beneficiary, or presumptive remainder beneficiary of an affected trust or estate shall have the right to make the election to continue operating under the law in effect prior to this chapter, which election shall be made by a written instrument delivered to, or executed by, the fiduciary and placed with the fiduciary’s records. The decision of whether to make such election by the fiduciary or by any income beneficiary or presumptive remaindermen shall conclusively bind all persons who may have any interest in the affected trust, including all contingent remaindermen and potential appointees of the affected trust or estate.