I believe they would. If the Western front turns out to be a stalemate like it actually was, then France would eventually lose due to attrition and british plus German naval dominance. As for Russia, as long as the Germans can pull off another Tannenberg, they should be fine. If the Germans throw most of their army at Austria, then Austria really doesn't stand a chance.
Also if you have Italy join up with the Brits and Germans as well as the Ottomans, that'd put even more pressure on the Austrians and Russians.
I agree with you that the Anglo-German alliance could win.
If the Anglo-Japanese alliance existed in this TL, then Japan could be tempted to attack the Russian Far East putting immense strain on Russia and its ability to fight in a two front war.
On a lesser note, it could also seize French Indochina, diverting French resources.
Also the UK and Germany combined possessed a stronger economy than the Franco-Russian alliance, so could outlast them in a lengthy total war.