Update: I was able to access my Sims 4 game through the new EA app today. I've only opened it once to see if it would open at all yet and it did. So, it looks like they may have fixed whatever was going on over the weekend.
NOTE: In case you missed the warnings about it: If you reverted back to Origin while the EA app was borked make sure you DO NOT run or have both launchers running at the same time or things will get ugly and break. Make sure the launcher isn't running in the background in your sys tray before opening the other one.