I am a bit surprised by the negative backlash of this suggestion. I would have expected more people to be interested in the opponent's country. Sure, it's nothing essential. Nonetheless, I do actually like the suggestion.
Well, pretty easy it could roll downhill when players would be able to identify their opponents not just like "that damn roping guy" but "that god damn unitless roping [insert nation] *@!". Maybe its not about you. But me personally - I don't really want international image of my country impact my online experience.
As an option, I wouldn't mind it. As an always-on feature, I wouldn't want it. I really don't care for always having -- and sharing -- that info since it's irrelevant when it comes to playing the game. (I never add opponents as friends or interact with them beyond the emotes and GGs.)
Seems the devs like toggles a lot these days, so it probably would be toggleable if it were in the game.
I think we would see a lot of "all the players from this or that country never gg" or "only play this anoying deck" etc. And there are countries having difficult relationships or even are at war (yes, real war) with other countries. We don´t need that in Gwent.
ProNeo's case is a really decent example why the matter of nationality is unhealthy for the community. Suddenly instead of discussion whether was he cheating or not, we have persons claiming that all the fault is either on CIS or EU citizens. Just keep nationalist politics out of Gwent, please. It is and should remain a card game played for fun, not an arena between competing nations.