Time-dependent backreaction corrections of the renormalized expectation value of the stress-energy tensor operator of a massless quantum scalar field, minimally coupled, in the two-dimensional spherically symmetric nondilatonic Schwarzschild-de Sitter dynamical black hole metric, is applied to determine the final state of its thermal radiation. Renormalization theory in the two-dimensional analog of a generally curved space-time reduces to a trace anomaly defined in terms of the Ricci scalar. So the regularized stress-energy tensor, in close relation to the work by Christensen and Fulling, may be obtained by the nonlocal contribution of the trace anomaly and some suitable parameters. Linear-order, time-dependent solutions of the metric backreaction equations, in close relation to the work by Bousso et al., show that the spherically symmetric nondilatonic evaporating Schwarzschild-de Sitter dynamical black hole final state, reduces to a set of remnant, stable, mini black holes where their metric should be described in terms of some permissible discrete Eddington-Finkelstein advance times. Also the results of this article are confirmed by the consequences of time-independent backreaction solutions which were derived recently by the author and may propose a new approach for quantization of gravity, in which the cosmological constant and a distinguished observer have a key role.