The impact is heavily uneven. Published measurements range from a barely detectable effect on transactional queries to reductions above 50 % on informational ones, and the pattern most analyses agree on is that the loss concentrates where the answer is a fact or a definition. Queries where the searcher needs to compare, buy or contact someone are largely intact.
The strategic response is not to abandon informational content but to change what it is for. Content that exists to attract a click on a definition is a declining asset; content that demonstrates expertise, carries original data and supports the commercial pages is not — and it is also what gets cited inside the overview, which builds awareness even without a visit.