I'd say that the Brits will get as much of Africa that their allies allow them too, as the Russians probably don't want to create a massive new threat for themselves which could lead to France retaining a portion of its African empire. Britain will keep Madagascar definitely but with the up coming unrest in Ireland and the rest of the Empire they might not want to take too much, as this war would probably aggravate the subject peoples as much as WWI in OTL. I don't see Prussia taking Alsace Lorraine but rather taking the South German states becoming the German empire before WWI w/out A-L.