I doubt households and businesses would immediately adjust their expectations up to the new targets and that expectations would then be well anchored at the new higher levels. Instead, I fear there could be a long learning process, just as there was as inflation trended down over recent decades.
Second, 4 percent inflation may be higher than can be ignored, and businesses and households may take inflation more into account when writing contracts and making investments, increasing the odds that otherwise transitory inflation would become more persistent.