I am doubtful that Latvia legalizes SSM soon considering that a 2016 Pew survey showed only 16% support by adults in Latvia. Incidentally it's the only country I can think of in Europe where the traditional Protestant church has remained socially conservative to this day, with its Synod voting in 2016 to restrict ordination to men only. Things can change, but all the data I have seen places it pretty far down the list of candidate countries to do so.
Well its neighbor Estonia just legalized SSM.
And with Russia adopting anti-gay rhetoric as a form of Russian nationalism, other countries from Ukraine to Poland to Estonia have begun embracing gay rights/pride.