It is true the New World is up for question with whether the French can establish a viable settler presence there, but the "natural borders" of France will result in a France with significantly more wealth and people. True, the French financial system will still be less effective, but adding on the better part of 10m people from the parts of the Left Bank and the other territories the French had gradually expanded into throughout the 17th century, by 1600, is a major boost to the French. Even later, it is still a major benefit, and furthermore the defensive advantages are real; trying an opposed crossing of the Rhine with fortifications defending the line on the other side must certainly be more difficult than fighting through the plains of Northern France, even with the fortifications the French erected. Even if the French don't divert resources from their army to their navy, their navy is going to be significantly more capable, and resultantly it would be entirely possible that wars between them and the British would go the other way in some instances. All it takes after all, is the French attaining command of the channel once, at which case an invasion of Britain is certainly possible and the French have a decisively commanding position in negotiations following.
So while I would say it doesn't guarantee victory and isn't necessarily decisive in of itself (as compared to having it in the 1800s when control of such territory would do much to help result in a more industrialized France with control over the coal supplies in the region), in the 1600s-1700s such an addition to French strength can easily change the balance of power significantly into the French favor. It isn't like the French were abysmal at utilizing their strength, just that their financial and economic system had more trouble in the war that the English was fighting. There is a percentage cap on French military strength so far as I know, not an absolute cap, so therefor a larger, more populous, more economically powerful France will be able to achieve a higher military strength, without any alterations to their systems used to raise such a strength. Even if they don't send more settlers out, they can do better in the New World after all by crushing the English navy and preventing them from sending out troops and reinforcing their own colonies. Preventing losses like at Acadia improves their settler position as well.