Not even close to being true, unless you specifically mean 10Gbps over twisted pair (Cat6/7) cable. SFP+ is the default on a ton of network gear still.
I think the point he is making is that the industry first went with a 10g single link, and then 40g over 4 links. Then they figured out how to do 25g over a single link, and 100g over 4 links. Those 25g/100g are common for enterprise switches. It might be fairer to say 40g is dead, 10g still has use cases.
Edit to add: If you want an example, these are the NVidia ConnectX nics available from FS.com, the lowest end one is 25g, then 100g, 200g etc.
What they mean is that the cost per bit both capex and opex/power is worse for 10G than 25G for a while now as long as you talk about new hardware.
We're at the point where 25GBaud PAM4 is being replaced by 50GBaud PAM4.
That's 50 to 100 Gbit/s.
But iirc the use of PAM4 for the faster ones than "only" 25Gbit/s lanes is a hindrance to managing bottom-barrel price-per-bit.
PCIe 3 was 8, PCIe4 was 16, and PCIe 5 is 32 GBaud with a line code basically like the 10+ Gbit/s Ethernet links (well, it's 66b/64b for Eth and 130b/128b for PCIe).
Edit to add: If you want an example, these are the NVidia ConnectX nics available from FS.com, the lowest end one is 25g, then 100g, 200g etc.
https://www.fs.com/uk/c/nvidia-ethernet-nics-4014