I hope ISU accepts Russia's request.
And, I hope ISU will give 1 men's spots and 1 dance spot to Korea in 2018, no matter Worlds outcome.
As the OP said, the host nation gets one, but I'm not sure if the TES rule would apply. However, Korea has a promising junior dance pair training in Russia; they might well be ready for 2018.
Rebeka KIM / Kirill MINOV
http://www.isuresults.com/bios/isufs00054325.htm
They were 6th recently at NRW Trophy Junior Dance.
Also Jin Seo Kim, a Korean junior skater who has several more years of junior eligibility, scored a bronze medal at one of his JGP events and a fourth place at the other. It's not at all far fetched that he might qualify for 2018 without the benefit of special ISU interventions.
http://www.isuresults.com/bios/isufs00013480.htm