Sorry, it just doesn't make sense for the Entente to collapse due to a shortage of US loans when there are other financial, logistical, tactical considerations to consider, whether it's the success of convoys, the stalemated trench war on both sides, the fact that the us made some threats about loans shouldn't mean much. The US wanted to support England more than official policy showed, but it stayed officially neutral for much of the war. Still its threats to both side were not actual actions we can talk about that took effect. They were talk that never turned to walk.
Collapse is a strong word. Thanks to financial tricks, the Entente isn't going to implode overnight, but they will have to make deep cuts to their war effort to keep it going. The first casualty is going to the British blockade, as they will be unlikely to be able to continue the policy of monopolizing trade with neutrals to keep them from trading with Germany.
The British could go off the gold standard too, but that seems to have been a step too far for the conservative government in London.
US support for Britain fell off as the war went on and Wilson got more fed up with the behavior and hard line the British government took. Greece and the blockade raised some real issues with Washington, especially the 'Black List'. By late 1916 the failure of the Entente to even play Wilson's game and offer peace terms, which the Germans did, really soured the Entente to Wilson. By early 1917, before the Germans started their Uboat offensive, Entente stock was at an all time low in Washington, about the equal of the Germans in the eyes of many. Even Wilson's pro-British advisor, Cl. House, was dropped from Wilson's graces.
Convoys and rations were making things better for the entente, not worse.
I don't see how the industrial power that was England during the 1800's was weaker in the early 1900's during WW1 vis a vis Germany than in the mid 1900's during WW2. Britain was an industrial powerhouse with colonies around the world and access to materials and finances from within their home territory and abroad. Germany was powerful, sure, but during the WW1 defeat, they cannot be said to have been at their economic or military peak any longer. In fact, what about Germany's Turnip Winter and the flue, why make Britain look weaker during WW1 than Germany?
Germany surpassed Britain industrially in the early 20th century, becoming the world's second largest economy by a comfortable margin in 1914. 1939 only increased this gap between Britain and Germany. A large part of the reason is that Germany came from behind and wasn't united until later, so had excellent examples to base their industrialization on. It was also state-directed, which allowed them to avoid the issues that plagued the British economy after their haphazard industrialization throughout the 19th century. Furthermore Germany had a larger population and a central position in Europe, plus a history of craft goods, so they had excellent room for expansion.
British colonial control is often overblown. They didn't have the right often to just demand things from their colonies and appropriate them, most of their colonies were alliances with local elites, which required the British to pay for what they used. Also in early 1900's the colonies cost Britain money rather than being a boon to her economy. She had captive markets and resources, but these were often purposely kept underdeveloped and could not buy much, while also producing only certain goods. Plus most of it was too far away to use in war time reliably. That is why the US was such a good source of everything. It was far cheaper to use and much closer. To import from Asia would require more than 4 times the distance to travel for her ships, while often places like India had troubles of their own. Food shortages and famine resulted more often in Britain being forced to import food to India rather than being able to use it to feed the British.
Also there are issues of cost. Britain refused to debase her currency by printing money and was quite leveraged. To import from Asia would mean having to pay more than 4 times the shipping cost and expose her ships to German raiders for longer, plus stretch the British escorts even more. Losses in ships would be that much more painful due to the longer delays in bringing goods in from the colonies. If you can provide sources that the colonies were good sources of food and raw materials, please do, because AFAIK outside of Australia and Canada, which didn't have all that much to export, the African and Asian colonies didn't really have metals and coal to export to Britain, nor oil (remember that the Middle Eastern oil was barely starting development in 1914 and the US was the primary source of world oil).
Plus Britain was dealing with guerilla wars in Persia, India (Pakistan today), and Afghanistan throughout the war, not to mention Lettow-Vorbeck in Africa, who wasn't receiving any supplies from Germany.
All of this ignores France, who was wholly dependent on Britain for raising loans and guaranteeing shipments of materials for her industries. Britain would survive without loans, France would wither. Remember Winston Churchill wrote in his history of WW1 that without US loans the war would have ended in 1917 due to negotiations, because it was impossible to fight without sufficient resources, financial and otherwise.
Germany had its share of problems too. Much, like the Turnip Winter, were self inflicted due to a change in leadership and terrible mismanagement of the economy by Ludendorff. The issues were corrected and in 1918 the German food situation was actually better than during the Turnip Winter. The flu arrived with the Americans in 1918 and spread to them once the US soldiers entered into the trenches. Prior it wasn't an issue.
Germany wanted and probably needed peace in 1917, all except her generals/dictators at the top. But without a willing partner, which a loan-less Entente would be, she had to fight to the bitter end.
And the more serious stuff another time!