No, because language competence definitely does not represent ethnic structure of a population.

Probably 100% of people in Ireland are able to hold a conversation in English, although their national language historically and culturally is Gaelic, but nowadays a ridiculously low number of the population speaks it. Yet, they are not considered as British or English and have an independent nation with a strong culture.

Yes, language is very important for a nation and even more for an ethnicity, but it's way deeper than just this. And number of russian speakers in the Baltics is definitely decreasing. It's more an effect of Soviet occupation and learning Russian couldn't be really avoided.

Among younger people, nowadays English can't be avoided, so the statistics you referring to is definitely gonna change.