trend of restoring Japanese mid 70's onward sedans is growing. I believe by 2022 JDM 660 will die and be sold by weight. KE series Corolla, Daihatsu Charmant, Datsun 120Y prices have rocketed up. So are the parts price in Scrapyards for such vehicles.
Lack of engine rebuilding new parts for JDM 660 is key factor for all those ending up in car graveyards.
Pak Suzuki is only company outside Japan with MITI authorization to assemble / produce 660 cc vehicular engines.
i doubt if any other Japanese Auto brand will go for 660 cc class hurting their brethren Suzuki.