I'm very curious to find out if Delta intends to eventually roll the suites out to the A333/A339 and the 764s. The timeline for the A339s is delivery from 2019 forward, so they're a long ways away. And presumably the A333s are still half a decade or more away from an interior refresh. So they could just be sitting on the details — otherwise it represents a major shift in Delta strategy, where routes truly become isolated to plane type.
Whatever the case, I highly doubt any of the 763s will see suites.