He acknowledges the root cause:

It’s hard for the government to increase the share of adults who are working, and there’s little that can be done in the short term about the country’s aging workforce — the result of a long-term fertility decline.

Source: Opinion: Boost legal immigration to ease labor shortages

Immigration is viewed as a solution by all economists; however, every country in this situation says they will solve their labor issue with immigration. Obviously, not every country can be successful with this as there is unlikely to be enough skilled immigrants for all.

Some countries will be more attractive than others, and they will achieve some success with this strategy.

Labor immigration tends to favor some industries over others. In 2000, the US Department of Commerce estimated 28% of all software jobs requiring a 4-year degree were filled by temporary H-1B visa workers. Others argued this enabled the software industry to engage in age discrimination. Due to the fast pace of change, experience beyond a few years is seen as adding little value. It’s viewed as more effective to hire a 20-something with 3-5 years’ experience than an experienced software engineer in their 40s or 50s. The result is rather than an expanding workforce, we add new young workers as older workers leave the field – and due to temporary immigrant worker visas, we continually fill the short pipeline with more young immigrant workers. Thus, the impact of increased “immigration” may affect some U.S. workers worse than others, which leads to opposition to immigration as a solution.

Economists, most of whom are tenured academics, have no trouble advocating more immigration – their own jobs are secure.

Coldstreams Skeptic