It's an excellent question, just made me think of my current infrastructure setup and also the future requirements.
We have 4 Node A300 in our current environment and probably the last ones to have UTA2/CNA cards. As you pointed out, I checked the HWU for A800s & A400s and discovered that 'UTA2' are no longer supported, end of an era.
I guess with All-Flash market, focus is on the speed of IO and processing. WIth multi-core CPUs and NVMe SSD Enclosures, the future is looking at more efficient protocols (Alternative to SCSI, in order to make the best use of the back-end & fron-end NVMe based SSD enclosures, and the answer seem to be these protocols NVMe/FC, NVMe over RCOE and NVMe over TCP/iWARP'). Therefore, all these Mean-Machines are focusing on the future technologies. It's not that bad, b'cos even existing dedicated FC infrastructure with gen5/6 switches can use the existing Hardware (same fabric & HBAs) to send 'NVMe' rather than 'SCSI', so both can co-exists until SAS based enclosures are completely gone (still many years to go) in your current DC.
It is believed that FCoE had low adoptation mainly down to specialized adapters (CNAs/UTA2-NetApp) and specialized high-end Ethernet switches.
Coming to queries: Query1 : Is that the end of FCoE support? Yes, indeed for the FILER models you mentioned.
Query2: I see that in the A400/FAS8300+8700 the onboard 25gbe ports can go down to 10gbe but the expansion adapter cards only appear to be 25. Yes, it is 25gbe, and they will only work at 25gb supproted speed. However, there is an option for 10gbe SPF+ [4p 10GbE SFP+ Cu|Op]. Please have a look at the A400 rear panel and cables info in the pdf attached herewith. The pdf is downloaded from hwu.netapp.com.