They get a much stronger alliance. Not saying Russia was particularly godlike in this period compared to other times, but at least it has a lot of people and resources and it secures Germany's eastern flank. Austria-Hungary was an extremely useless ally, and a German-Russian alliance could take it down very easily in the event of a war and then just focus on France and/or Italy and/or the Ottomans depending on how the other alliance block works out.
In the immediate term though we likely get super-Bulgaria. Germany would probably still allow Austria-Hungary to occupy Bosnia as a sop to try and maintain an alliance with the Dual Monarchy.
Seconded. Austria-Hungary's position is hopeless if Germany and Russia are allies. Eventually A-H and Russia agree on how they want to divide the Balkans, and the Ottoman Empire ends up partitioned one way or another.
I assume that the question is never Austria OR Russia - its definitely Austria and Russia or Austria alone.
But assume there is a Russian German Alliance 1880+
This will force Britain to delare early and you probably get a Brit-French-Austro-Ottoman alliance in the 90s. Strictly Military thinking A-H is in dire straits, but that will possibly be stabilitzing the Empire and Hungary might allow a bigger share for the Military in the financial negotiations. The Caropathians will become the line of defensive. The Bohemian landscape will be used for defence too. Austrai will have to hold until France marches into Berlin ()