France & Russia together with Britan where not strong enough to beat Germany in this timelime. How are the gonna threaten Germany if they start from a much lower power base?
Germany =/= CP. Easyto forget as they were by far the strongest of the CP but dont forget that AH put many millions of man on the field, and dont forget Bulgaria and the Ottomans. In a late german victory A-H is likely gone and the ability and willingness of the successor states to support german war effort might be a lot less. Not to mention if some of them goes red like OTL Hungary. Turkey too might not be willing to go for a second round if they lost out on the first.