I'm not so optimistic about the ECHR simply ratifying the Norwegian government's decision. Two points, courts are generally very conservative and this appeal will come from a position of freedom of religion, a basic human right. ECHR has "human rights" in its name.
Point two: Norway's decision is an outlier. No other European governments are showing any signs of doing what Norway did. A European Commission is more likely to reflect attitudes of the broader European community, rather than the one country that decided it had had enough of the WT's shenanigans.
One of my personal mottos is "Never go to law". Most court cases are a coin toss. Unless you are really sure you're going to win, don't take the chance. The WT should follow that advice and not appeal to the ECHR. They should take their medicine, take the "L" and keep softening their approach to disfellowshipping.