Stats about Schlieffen Plan:
Before the war started Moltke jr transferred 4.5 corps to the eastern front, 180,000 men, from the right wing.
Between 1905 and 1914, 9 more corps became available. 8 went to the left wing, 1 went to the right wing. Schlieffen would probably have done the exact opposite, ie 7 more corps on the right, thats 280,000 men (assuming 40,000 = 1 corps?)
When the French became bogged down in their attempt at Plan 17, Moltke jr decided to dispatch 2-3 corps from the Sixth army to "Pursue Direction Epinal", thats 100,000 ish men lost to the right wing again.
Then we have the 2 corps sent to East Prussia that never made it there in time, 80,000 men lost.
Tally up the figures and you get 640,000 more men for the right wing.....much better chance of success, albeit still a gamble.
Take into account also the original plan called for bypassing Liege, since the German armies would move in a wider arc, faciliated by passing through Dutch Maastricht. They would have taken the Channel Ports en route to Paris, meaning very difficult British landings.
As for the suggestion of scrapping the plan altogether, earlier war plans had indeed envisioned defence in the west and offence in the east. Moltke sr. and Waldersee had considered France to be a fortress, incapable of easy breaching, so the focus should have been on the east.
As for the notion that Britain would have declared war on Germany despite a defensive war on the west and nonviolation of Belgian neutrality, I would say wrong. The mood in Asquith's cabinet was very anti war until the Germans were marching through Belgium, threatening the channel ports.
24th July 1914, Asquith wrote "Happily there seems to be no reason why we should be anything more than spectators [in the coming war]". The notion of Germans just across the Channel changed all that. It was highly unlikely that the British army would be fighting a French war of aggression in Alsace Lorraine; the British were prepared to defend their ally, not march with them into senseless offensives on German forts.
And if you want to go back further, the Bismarckian system's continuation would not have seen Germany diplomatically isolated (Austria and co. dont count as significant) by 1914. The Iron Chancellor did not instigate any war after 1871, and was satisfied with the German Empire he had helped to create. Only the mentally ill(?) Wilhelm II decided to go for the idiotic Tirpitz Plan and the "place in the Sun". A Friedrich III ruled Germany would probably not go to war with Britain.