Of course, there could be more helpful changes that would complement the above:
Return to educating users about https + domain names. It is way simpler and more effective than what is taught now (a form of "email psychology").
Return to the practice of putting subcontracted IT services under the contractor's own domain. None of this stuff we see today where a Firstbank.com user gets shunted off to myfunkybankingsvc.net without warning. Same for outfits that deliver documents via email on behalf of a primary org.
Improve security of personal devices (esp. PCs, phones) with new architecture that can isolate threats much more simply and strongly; namely microkernels and bare-metal hypervisors. Proliferation of malware on personal devices undermines society's confidence in mundane net security measures (as described above), pushing people towards snake oil remedies and/or authoritarian control (see Apple & Google app stores).
TBH, looking at the above, the impact of phishing and malware could be a fraction of what it is today for relatively little effort. Somewhere over the course of the last 25y the IT industry talked itself into selling dubious palliatives that took the place of properly engineered security developed in accordance with computer science.