for example react is listed as high risk, but at the same time i would consider the risk to be very low in the sense that if it is relicensed then it will be forked immediately backed by a community that is strong enough to sustain such a fork.
i'd go as far as saying that for react relicensing would kill the project because the majority of users would go with the fork.
for other projects the risk is higher because they don't have a strong FOSS userbase that could sustain a fork, and because most current users would not care.
One challenge for forks is that relicensing doesn't always jump from fully-open to fully-closed. There's a lot of "fake open-source" and source-available licenses, like the one Redis now uses. These may "only impact you if you are AWS", so a fork "that AWS can use for free" feels less compelling. If React was to relicense, I expect they'd similarly take a small step.