This chapter shall remain in force and effect so long as the United States Government retains in full force and effect, as a part of the revenue laws of the United States, the present federal estate tax, and this chapter shall cease to be operative when the federal credit for state death taxes set forth in 26 U.S.C. § 2011 [repealed] is repealed completely for the estates of decedents dying on or after January 1, 2005.