Okay. Well, you should wait for benchmarks. If like in the anandtech article mentioned the clock rate gets decreased, and that would be very normal when adding more cores, then a single thread performance increase is very unlikely. In the last launch Intel did not get close to those numbers, and that was without a core increase.
Also, there seems to be some confusion whether those processors now are a kaby lake refresh or the new coffee lake architecture. The videocardz article mentions Coffee Lake (and some other news articles call those processors that as well), but the anandtech article defines them as a Kaby Lake Refresh. A new architecture would make a single thread performance increase more likely.
The table in the article shows a ~5% increase in boost clocks for the high end models. Those are what matters for single-core performance, not the base clocks.
I think that would be correct for the Desktop, but in laptops the turbo clock normally(?) does not work for a sufficient long time to give it any meaning.
It does in well-designed machines, although usually not in the ultraslim ones. The ThinkPad T470 can sustain full turbo indefinitely according to notebookcheck. Lenovo's premium line (X1 Carbon/Yoga) cannot, though, as they're too thin and light for a sufficiently capable cooling system, and will throttle after a while.
Also, there seems to be some confusion whether those processors now are a kaby lake refresh or the new coffee lake architecture. The videocardz article mentions Coffee Lake (and some other news articles call those processors that as well), but the anandtech article defines them as a Kaby Lake Refresh. A new architecture would make a single thread performance increase more likely.