Quintessence’s last stand?

Current cosmological data puts increasing pressure on models of dark energy in the freezing class, e.g. early dark energy or those with equation of state w substantially different from -1. We investigate to what extent data will distinguish the thawing class of quintessence from a cosmological constant. Since thawing dark energy deviates from w = -1 only at late times, we find that deviations 1 + w less than or similar to 0.1 are difficult to see even with next generation measurements; however, modest redshift drift data can improve the sensitivity by a factor of two. Furthermore, technical naturalness prefers specific thawing models.