10gbe will depend on the workload. In general, I'd assume it's fine because it takes a parallel raid setup to saturate. Upgrading to 100gbe is pretty unreasonable cost wise unless you buy network gear from a back alley van dealer.
Although once you reach 4 2080ti, you ought to consider switching to a titanium grade psu and rewiring if you're in a 100-120v country. If you're feeling cheap, just steal the phases from two different circuits. Last I looked, most psu operate around 5% lower efficiency on 115 vs 230.
I've encountered some latency issues with allreduce on transformer models due to vocabulary sizes when communication have to cross PCIe lanes. Increasing batch size helps a lot, but low-latency & high-throughput is universally more helpful to lift these minor concerns (I don't really want to care about my batch size to improve allreduce performance). Hence worried not only throughput, but also latency on consumer-grade 10ghe equipments.
Although once you reach 4 2080ti, you ought to consider switching to a titanium grade psu and rewiring if you're in a 100-120v country. If you're feeling cheap, just steal the phases from two different circuits. Last I looked, most psu operate around 5% lower efficiency on 115 vs 230.