True, but Belarus was always rather submissive to Russia, I'm not sure this is a news for Poland...
If Russia could accept NATO in Baltic states, Poland will have to accept Russians in Belarus...
Regarding the Baltic states, Estonia and Latvia both have a significant Russian minority of around 25%.
I'm counting on their Finish-like mentality to find common ground with their neighbors, because otherwise this region could be a real mess.
Estonia has one region where Russians make 70% of population:
Ida-Viru County - Wikipedia
Latvia, percentage of Russian, Belarusian and Ukrainian minority:
They also seem concentrated in a couple of regions...