Not so much the crankshaft (which is inside the engine), but more the transmission and remaining driveline (driveshaft, differential, etc) become the new "weak points".
This assumes that the Ecoboost version isn't just a engine swap - it could be that Ford uses everything the same from transmission back, and just pops different engines and badges on. I don't know if this is true or not, though.
For instance, on their old Ranger pickup trucks (basically rebadged Mazdas), the rear axle on virtually all of them was way over-engineered vs the rest of the pickup:
While there were some differences between models, most of them used one of two sizes, and they just dropped a different engine and transmission in. In this case, depending on what you had, you might end up breaking other parts before the axle gives (the Ranger axles are a popular swap upgrade from the Dana 30 axle on Jeeps, due to it's robustness)..
This assumes that the Ecoboost version isn't just a engine swap - it could be that Ford uses everything the same from transmission back, and just pops different engines and badges on. I don't know if this is true or not, though.
For instance, on their old Ranger pickup trucks (basically rebadged Mazdas), the rear axle on virtually all of them was way over-engineered vs the rest of the pickup:
https://www.therangerstation.com/stock-ranger-specifications...
While there were some differences between models, most of them used one of two sizes, and they just dropped a different engine and transmission in. In this case, depending on what you had, you might end up breaking other parts before the axle gives (the Ranger axles are a popular swap upgrade from the Dana 30 axle on Jeeps, due to it's robustness)..