There is the possibility that some sort of low-intensity conflict involving one or two major powers but not a pan-European war could shake things up in regards to tactics, then again, it took four years of war plus tanks to do that OTL.
But the thing with trench warfare was it was a response to the conditions of the time, artillery was more lethal than ever before and so were things like machine guns (which caused easily the highest casualty rates for the charges across no man's land), but there were larger political reasons for it as well. In that department, it all boils down to the Schlieffen Plan, Germany knew she would be drawn into a two-front war if she fought and stalemated the Western front on purposes so she could take the Russians out, the Russians being a slow-mobilizing but hugely-populated empire that would be a huge problem otherwise. The Eastern front of the war, and the Austro-Italian front, as I recall, were both rather mobile but the thing with those fronts was that most of the sides involved were the second-tier European powers with the exception of Germany.
No Schlieffen plan or (somehow) no Russian entry might do the trick, that would have to butterfly the original crisis and not threaten directly any Russian interests... though Czar Nick would still be a fool to drop his allies.