In the event of the entente defeating the Central Powers by 1917, before the Russian Revolution or US entry, I can't help but think that once the "German Question" is resolved that the basis for east-west alliance against the center would go away.
Russia likely absorbs Posen, Galicia-Lodomeria, Bukovina, and Upper Silesia in Europe.
In Asia, Russia will gain the straits and Wilsonian Armenia.
Yugoslavia/Greater Serbia would Russian-aligned.
Czechoslovakia had a strong pro-Romanov faction and thus would be Russian aligned under a Romanov.
With Czechoslovakia to the North and Serbia to the west, I can imagine the Russians "persuading" Horthy to put a Catholic Romanov on the throne of Hungary.
The Polish Corridor + Danzig goes to Russia TTL, with East Prussia either being demilitarized or established as a Hohenzollern rump. A sliver of lower Silesia east of the Oder and Eastern Pomerania are demilitarized as well.
Russia, now on the Adriatic and with control of the straits, poses a geopolitical threat to both Britain and Italy. Germany, Denmark, Sweden, and Norway likely are insecure. France, in a bid to try and avoid German rearmament, might join the anti-Russian bloc and/or tie Germany to France (think something like the Briand-Streissman European Federation ideas).
