Update (Aug. 8, 26): Bloomberg's Mark Gurman dropped a report this morning claiming that the all-glass iPhone 20 is not canceled. "Apple Inc. is still planning to offer a glass-centric overhaul of the iPhone for the device’s 20th anniversary," Gurman said.
Apple's designs are reportedly "mostly locked in" and in advanced testing a year in advance, barring any mishaps. Gurman noted that the design will feature some metal holding the two glass halves of the phone together. The iPhone 20 is supposed to be seamless, it's unclear if this metal band will be visible or not.