That's what Ingo is referring to. "Unfortunately there's a nostalgic cost: your [i.e. Linus'] old original 386 DX33 system from early 1991 won't be able to boot modern Linux kernels anymore. Sniff."
I sent my original 40 Mhz 386 that I used when hacking Linux 0.12 back in 1991 to be recycled last year, after it was displayed on exhibit at Linux's 20th year anniversary party. I tried to see if anyone (like the Computer Museum) wanted it, but ultimately, I'm not the nostalgic type either.
Turns out Linus is not the nostalgic type.