The 100base-T1 and 1000base-T1 standards already exist, and are already widely adopted. 10base-T1S is intended to replace CAN, which is sub-10 Mb/s, and often ~2 Mb/s; this is a niche where cost comes first. For non-multidrop links, intermixing 1000, 100, and 10 Mbit/s ethernet links on the same switch is trivial, so each link can be independently chosen and cost-minimized; and for sensors and high bandwidth items with safety impact, multidrop is generally not the preferred approach anyway. Basically -- 10base-T1S fits a new niche (for Ethernet), where the niches you mention are already well addressed.