Long gamma-ray bursts (GRBs) at high redshifts are unique and promising probes of the early universe in answering questions including: How did the cosmic star formation history evolve? When and how did cosmic reionization occur? What processes governed the chemical enrichment history? In Lidz et al. (2021), we forecasted the reionization history constraints, inferred from Lyman-alpha damping wing absorption features, for future samples of z > 6 GRB afterglows. We consider an afterglow spectrum model described by a set of 3 parameters: the size of ionized bubbles, the neutral fraction of the IGM, and the column density of local damped Lyman-alpha absorbers (DLAs). We apply a Fisher matrix analysis to forecast the constraining power on the IGM neutral fraction evolution from spectroscopic follow-ups of future data sets of high-z GRB afterglows.