I fly SK very rarely so my guess is as good as any.
I see two options on implementing this, either segment the market
a) by country of trip origin and then CPH will be danish even for swedish pax
b) by issuing country of credit card and then swedes (and others) may be exempted from fees
LH and AY does the first, so I'd say it's more likely for SK to do the same.
SK's reasoning in the articles linked above is a bit lame - as more sales are driven to the web (as part of 4excellence strategy) there really is no other viable option for payment. Therefore this is a hidden fee. Or will they add bank transfer and invoice as payment methods?!?
Trouble is - people are stupid. They rather pay 50€ in fees instead of paying 45€ extra for a ticket without fees. SK cannot overlook this irrational behaviour of travellers.