STP obsolete for over a decade
STP has been obsolete for over a decade, multiple protocols from multiple vendors are have been good alternatives to STP long before TRILL was a twinkle in anyone's eye. It's kind of funny and perhaps sad that the majority of folks don't seem to have realized this.
also the article doesn't mention the use of 802.3ad as a stopgap for faster ethernet, You can combine at least 8 links together to form a logical connection, with MLAG I think you can at least double that number if I recall right. This is of course widely deployed now and has been for years/decades(except MLAG which is kinda new)
"It's possible, we suppose, but unlikely that new Ethernet standards will evolve to cope with this, ether by specifying latency at a switch level or at a network level. "
We have that today too, it's called routing protocols, what do you think this hyper scale network with tens of thousands of switches would be a big flat layer 2 network? what a disaster that would be!
Be mindful of the costs of 100Gbit ethernet too. If your running a cross pacific undersea cable then costs for the optics probably aren't a big deal, but for most other sorts of deployments (intra data center at least) 100Gbit ethernet just isn't worth it today from a cost perspective.