Victor Michel's plan was a good plan made by a lucid commander but it completely ignored the realities of French politics in the 1910's. It was way too much defensive. If Victor Michel had sold the plan as a "defensive first, epic counter-offensive second" instead of a "slowing then stopping the wave", it could have worked. Sometimes simple choice of words are enough. If he had presented a limited offensive on Metz, the only area that mattered on a strategic POV for a long war (tons of iron of good quality), with his generally defensive plan, it could have been accepted. Victor Michel probably had guessed that the war would be a long one. 1914 was not going to be the decisive year, 1915 was not going to be a decisive year etc. OTL, the Entente uderstood and accepted this in 1918. If Michel can convinced the government that the war will be one war of attrition, the plan XVI would been less of an outrage for the politicians.
Let's assume that Michel is "politically" smart enough to slighly modify his plan:
Step one: we let the germans come like waves against the rocks. That would need more MG or LMGs (the chauchat has already a prototype in 1911!) and a longer range field artillery (like the 105 mm also ready for production in 1911). We inflict them tremendous casualties on a rougly Anvers-Namur-Verdun line then slowly retreat in good order. Repeat that two to three times. At the french border, full stop. Counter offensive (like the Marne), force them to retreat to square one. That need two things: first, no three-years law but instead use that money to train the reservists with extra weeks. With this, you implement reservists regiments within the active divisions. Basically, the number of combat ready -relatively well trained units- divisions in Agust will increase of 25 percents. Second: Break you five big armies into 7 smaller more mobile one (basically 8 divisions with two in reserve with tree corps of one). Also trust someone like Blaise Diagne and Mangin to recruit volunteers in the Colonial Empire (by using the 1916 recruiting policy, very efficient to convince the locals to go fight for france). If you begin this in 1912, you will have another field army of reduced size ready (the only thing to do now is the ship it in time to france, easy to do if it's considered as all-active army).
With that extra number of field armies (plus the BEF), you have the tool to properly outflank the german First army, possibly the Secondwhen you decide the "full stop" and Marne counter-offensive. Encirclement, partially close pocket, one army destroyed, another at least gutted if lucky. Then the Germans are down from 7 to 5 armies when you 7 armies (let's say you have lost rougly the equivalent of a small army too) plus the growing BEF. The Germans are forced to shorten their lines: so retreat back to a Antwerp-Namur-Verdun line.
If you show to the russians that you're holding the line for a sufficient amount of time, they won't rush their offensive in Easter Prussia: More time to mobilize, more divisions (roughly 60 at DAY+30). With this, if not a victory, this will be a bloody stalemate for the Germans down to 1 army in the east. Again: Germans forced to retreat along the Vistule.
In that moment, when the Germans are forced to pick up corps in the West to throw them in the East, you turn this into an impossible mathematical equation: offensive against Metz and the 5th army in a classical pincer movement. Even if you don't take Metz, it forces the Germans to be everywhere with a limited amount of men.
RESULTS: Northern France preserved with its ressources and industry, a Belgium at least half-Entente on a territorial point of view (coal around Namur) and a Coast secured for the British. Germans forced to adopt a defensive strategy with limited ressources (if Metz is taken or even in range for the french artillery, its mines are useless). Their losses: around 500 000 men. Yours: 200 000 (if you don't act stupid like Joffre OTL) plus the British and Belgian ones. In the East, Russia keeps two fields army and a Poland which is not encircled by Silesia and East Prussia: less troubles in the future. Against A-H, same as OTL.
The Ottoman Empire remains a wild card with the 3 august agreement and the Breslau going as OTL and still can declare war but in the same time, if Germany is clearly in the defensive and in difficulty, they might hesitate. Italy will be even more convinced to switch sides. Bulgaria, well between spetember 1914 and 1915, a lot can happen so I don't know.
As for Germany, either she sues for peace: lose A-L, Easter prussia, probably not Poznan, A-H lost Galicia/bukovina and perhaps Bosnia and Northern Serbia to Serbia. No heavy reparations, no limitations on German armies: that means a plausible round two not so long after. Or Germany gets stubborn. If Victor Michel is still in place, knowing the man, he will prefer limited and well planned offensives instead of the disastrous 1915 ones. Germany feels the first effects of a blockade, try Jutland, fail to kill the RN as OTL and go back home. War could end for fall 1916: Germany will probalby lose Posen and upper silesia this time. Belgium as OTL, Romania perhaps as OTL if she joins the feast, Italy as OTL, France will perhaps get sourthern Sarre according the 1814 borders.