SF: no real argument with the comments on US forces you make. I would never argue the US made no battlefield contribution in 1918.

Its speculation, but IMHO the 1919 campaign would have been a series of bite and hold attacks, much the same as 1918, but on a bigger scale. The limiting factor, I suspect, would always have been that once you outran the range of your supporting artillery, life got much harder, and WW1 artillery was not rapidly mobile. I can't see that the technology would have allowed blitzkreig tactics, since even the light tanks were not that fast, had not that much range, and broke down/got knocked out a lot. In other words, just like better infantry and artillery tactics, they were good at the break in, but not that good at the break out.

(Digressing, I reckon you not only needed more reliable tanks/transport, but also far better tactical air support in the place of artillery, for blitzkreig to be possible. Fuller might/might not have seen the vision but I don't think he could have achieved it)

But break ins would have been enough. The Germans were only going backwards after they were stopped in the second battle of the marne, and that was achieved without ever making a breakthrough.