Belarus: I could see CPB taking over when Lukashenko isn't in charge anymore.
Burkina Faso: Their prime-minister seems to be a communist. Hopefully this means working towards a socialist state.
Cyprus: AKEL is one of the main opposition parties in Cyprus and their candidate for presidency went to the runoff election this year.
Greece: KKE is one of the main opposition parties and they keep growing.
Haiti: There are some revolutionary organisations involved in the protests against the government, maybe they'll succeed.
Swaziland: The CPS is the main opposition to the king's rule.
Taiwan: through reunification with PRC.
What others seem likely to you?
EDIT: I remembered South Africa is a candidate as well, the EFF is getting stronger
I strongly doubt any country in Europe will have a successful socialist revolution until US imperialism is dismantled
(Taiwan is not a country by any definition)
Not even Belarus?
In terms of self-defense post-revolution: possibly, if it retained a defensive pact with Russia. Whether a revolution is feasible in the next few decades, I can't say