Maintenance for the week of May 25:
• PC/Mac: No maintenance – May 25
• ESO Store and Account System for maintenance – May 27, 6:00AM EDT (10:00 UTC) - 4:00PM EDT (20:00 UTC)
According to the announcement it's maintenance, not patch maintenance. I imagine it's the usual problem with console of having to get the launch version of a new content release with the platform providers in good time for their certification so that small last minute incremental patches aren't really feasible.