TIA adopted IEC 61280-4-1, the standard defining attenuation measurements of installed multimode fiber cabling, as ANSI/TIA 526-14-C.
In IEC 61280-4-1, the encircled flux launch is defined as normative (required) for these cases and there is no intention to change requirements in the next edition:
Case 1 - 50 μm core fiber at 850 nm,
Case 2 - 50 μm core fiber at 1300 nm,
Case 3 - 62,5 μm core fiber at 850 nm,
Case 4 - 62,5 μm core fiber at 1300 nm.