There are other reasons why flu vaccines don't work from year to year. For instance, this year there is evidence that vaccines made in eggs acquired mutations that limited the effectiveness of the immune response (https://www.statnews.com/2017/11/07/flu-vaccine-egg-producti...). Viruses made by other means don't seem to have this problem but are a lot more expensive and we'd need to retool the entire flu vaccine industry to solve this.