I did some digging here on Visajourney and it seems relatively straight forward to reschedule the oath ceremony, if necessary. You can mail a letter explaining why you need to attend a later oath ceremony to your field notice. Apparently, they will even automatically reschedule ONCE if you don't show up. (Not that I plan on doing that...) https://www.uscis.gov/policy-manual/volume-12-part-j-chapter-4
Also, thank you for the reminder - yes, the law only goes into effect 6/27, not 6/26.