No, I'm saying that e.g. Central Europe Time keeps being defined as "UTC+1" for the next few centuries until solar noon has drifted about 30 minutes away from c

No, I'm saying that e.g. Central Europe Time keeps being defined as "UTC+1" for the next few centuries until solar noon has drifted about 30 minutes away from civil noon, then CET's definition changes to be UTC+0 or UTC+0:30. This is a time zone update of the sort which happens constantly (e.g. in 2017, Chile changed its TZ offset, Haiti started using DST and Mongolia stopped using DST. A TZ offset change to account for clock drift would be exactly the same)