The nuclear share dropping is a very clear signal about a lack of investment. Shows that nuclear energy is no longer cost competitive, even in a "low regulation" environment.
chinese nuclear is extremely cost competitive at 2.5bn/unit. They have other reasons, one being the ban on inland expansion fearing of messing up with 2 major rivers that feed the country. Current chinese units are basically borrowed and improved western designs, cap is basically vogtle's ap1000, hualong is a frankenstein of several western designs.
It shows that strategic investment matters and people are looking at more than a single cost metric. Nuclear is behind today, but that doesn't hold a promise it will remain true into the future unless you stop investing now.
One armed bandit says explore as well as exploit. This delta you cited indicates the pendulum currently is more exploit than explore, but its not a static equation.