"unable to load the city at this time. Please try again."

Darn it! Here are a few other things to try:

1. Make sure your firewall and antivirus are not blocking SimCity.exe, and that it is added to the exception lists. I know when mine updates, it occasionally likes to change settings for no good reason. If you have BitDefender installed, disable it.
2. If you have any mods installed, remove them
3. Set the desktop icon to run SimCity as administrator
4. In Origin, right-click SimCity icon, Game Properties, check the box that says "Disable Origin In-game"
5. In Origin, right-click SimCity icon, choose "Repair Game"
6. Run SimCityRecovery.exe Default location is \Program Files (x86)\Origin Games\SimCity\SimCityRecovery. This can take a while
7. Delete everything in Program Files (x86)\Origin Games\SimCity\SimCityUserData. The game will download 
8. Delete all files in C:\ProgramData\Origin\DownloadCache (You might have to go into settings and enable viewing system files: Control Panel - Appearance and Personalization - File Explorer Options - View - Hidden Files and Folders - Check the button "Show hidden files, folders and drives" and un-check "Hide protected operating system files")

If none of the above works, you could try calling support to see if they can do a roll back. Otherwise, you may have an unrecoverable city. I hope this is not the case.