EM-1 was originally a full-up test of the SLS block 1B: Orion, ICPS (a modified 5-meter Delta cryogenic second stage), and the first stage/SRBs.
NASA administrator Bridenstine’s statement on 3/13/2019 suggested they might launch Orion and a fueled ICPS on two separate commercial booster launches. The two then rendezvous in LEO for the EM-1 flight around the moon.
This implies that, without other changes to the SLS program, the manned EM-2 mission would be the inaugural flight of the first stage and SRBs. On the grounds of safety, it is hard to see how the EM-2 plan would be allowed to stand. At the same time, neither of the two commercial boosters under consideration – Delta 4 Heavy (DIVH) and Falcon 9 Heavy (F9H) – are human-rated. SpaceX has previously gone on record to say that they weren’t human-rating F9H, and the DIVH production line is in the process of shutting down. Yet one of those vehicles would need to be human-rated in order to be used for further Orion flights.
So, other than developing and proving out a mission architecture that has waited half a century to be realized, what of the original purpose of EM-1 would be served, leaving what possible path forward for launching humans into deep space?