There was no likelihood of the US entering the war without USW. Until that happened their relations with Britain were if anything worse than with Germany. Indeed, had someone like Bryan been POTUS (a distinct possibility had things gone a bit different in 1912) even USW might not have done it.
As for the consequences, these have been gone over ad nauseam on more threads than I can remember. But, keeping it short, they'd have been enormous - more like albatrosses than butterflies. The Entente would have missed out on several billion dollars in unsecured loans, and all the material these purchased, while absent the American tanker fleet, the RN would have been in grave danger of running out of fuel oil in 1917. All in all, a disaster.
I like the general look of this, though I am unsure as to the complete uncertainty of American involvement at some point. A lot of Americans in those days were Irish or German immigrants, or had been born of and raised by the same, and they hated the British with a passion. A lot of newspapers and the like were owned by pro-British folks, however, and the British themselves tried to limit the ability of Germany to get information into the hands of everyday Americans, which influenced public opinions quite a bit.
I think without unrestricted submarine attacks on merchant shipping of all nationalities, it is likely America keeps out of the war, at least unless something else huge happens to draw her ire.