Federal Communications Commission Chairman Ajit Pai has threatened "regulatory intervention" if major phone companies fail to adopt SHAKEN and STIR this year. Most major US phone providers have pledged to do so. The technology would also have to be adopted by carriers in other countries in order to authenticate calls between US-based and international carriers.
This is a step in the right direction (and one of the vanishingly few bright spots of Ajit Pai's tenure at the FCC) but is nowhere near sufficient to tackle the problem long-term.
That said, even with RoboKiller in place, I still skip answering just about every call from a number that isn't in my contacts.