As a countermeasure against population decline caused by a lowered birthrate, the ruling Liberal Democratic Party (or at least a faction thereof) is proposing that Japan should aim for 10% of its population (128 million) to be comprised of immigrants by 2050, which would mean an additional 10 million on top of the current 1-2 million (depending on criteria).
The most immediate and concrete step towards this goal will be relaxation of the currently fairly onerous requirements for permanent residency, with the current system generally requiring ten years plus, and/or a Japanese spouse in order to acquire permanent residency, with acquired citizenship being almost unheard of; instead, they are recommending seven years for residency and ten for full citizenship, which would be on par with many European immigration regimes. Via Yomiuri.
Who knows whether such a long term policy will come to fruition, but if they wish to make a success of it they would likely do well to study the failed immigration and multicultural policies of the various European countries who have accomplished over the last fifty years what the LDP appears to be looking towards in the next fifty years, with some very mixed results.
Overcoming these difficulties will clearly not be straightforward, perhaps even less so for Japan with its even stronger barriers to integration, though the prize is certainly great should they achieve it.
It may be more straightforward to build the robots, although I suppose they may as well try both strategies… they could always use the robots on the immigrants if they become unruly.