Only way drop Russia already in 1916 is revolution and situation wasn't yet bad enough for this.
And even if Germany is able win WW1 in 1917, I just can't see any possibilities to mild peace terms. War had lasted three bloody years so not way that they wouldn't punish losers and take risk to secound round. France would notice that Germany is not even able push harsh terms so it would try again. And same with Russia too. Germany had made France and Russia weak and create buffer zone in east so that it could be dominant power in Europe.
I wouldn't nessicerily agree that Russia needs a total revolution to drop out of the war, or that with a little more pushing (Say, Lenin accepts the German offer for a free train ticket he was given in 1915) such a revolution was even unlikely. Already by early 1916 you had a substantial number of strikes in Russian industry, and that year's harvest woulden't be particularly good; if Romania starts making less helpful noises, or German-backed agitators or domestics nationalists are a little more successful (Say, the efforts by Georgian and Ukrainian emigres to put together insurgent armies are more successful, leading to proper centeralized uprisings), ect., and I could see the ultra-conservatives staging what amounts to a self-coup (Nappy III style) to "save the Tsar from himself"; possibly in response to a general strike organized by Socialists to demand major reform in exchange for further support of the war effort, necessitating the imposition of martial law.
As for the peace terms, alot depends on just what agreement Germany and Russia make. A moderate Eastern Peace might just be enough to convince Wilson of the CP's good faith and get the US to weigh in on the side of a mediated, balanced peace rather than entering the war on the CP's side. Plus, an earlier defeat of Russia means the distinct possability of at least delaying USW resumption, which will at least delay formal American belligerency until battlefield realities on the Western Front (The assertion is that a Spring Offensive is successful; let's ignore the French mutinies since they were against the policy of offensives anyways, so I doubt they'll withold any effort in trying to resist further encroachment on French soil) combined with a lack of formal US entry means the credit markets in the US start getting antsy about extending further loans. So long as her army and homefront are still both intact though, especially with diplomatic backing from Britain, France will hardly have to accepted a vanquished's peace, nor would Belgium (Though both nations would face major post-war economic problems). The big loser of the Western Entente would probably be the Italians, since nobody is going to stick out their neck for Rome, and Serbia is going to be left out in the cold.