Hi,
the optional choice makes sense with NAS or other computers with 10G interfaces in your studio. So for instance if you'll be doing some video editing with central storage or have studio with multiple workstations, where you often exchange data, I'd say go for that.
1G Ethernet caps you at approx. 110 MBytes/s of bandwidth, so for example with some 4K video and fluent work with certain codecs directly from NAS instead of local drives, you'll actually need that.
With audio over IP that's not really necessary, unless we're talking about some backbone networking at large sites, because you can easily transfer hundreds of audio channels back and forth over single 1G Ethernet from multitude of devices. So no, for this particular use case, I don't think, vendors of audio interfaces will be adopting 10G Ethernet ports.
Such move could be possibly motivated "just" by necessity of bandwidth increase, because isolated transport latency (not talking about total latency in your DAW, that depends also on used endpoints) of audio over IP connections is already very low (sub ms) and rather depends on complexity of network topology (eg. amount of hops) than bandwidth.. So they won't gain anything there by shift to 10G with regards to latency.
Michal