Guest workers are not immigrants - they are sojourners who fill needs in the labor market. Immigrant is defined as someone who permanently settles in a new area/country. There is a lot the West could learn from East Asian immigration policy.
It says some will be allowed to apply for permanent residency.
Also support for the change is highest among young people, so it may be a harbinger of the direction of Japanese immigration policy in the future.
O/c you could argue if a country with 100 mil packed in the size of Montana needs more people, but as Audrey says the population is expected to plunge.