I had been going to write up a brief on why your scenario couldn't happen, but I'll spare you the wall of text and just get to the point.
Germany and Italy combined didn't have enough Shipbuilders to out pace the US's naval rearmament buildup, let alone the materials with which to build the ships required.
By V-J Day, the US Navy's grand fleet held over 620 major surface combatants, well over half of them being new construction; had the construction draw down not happened, by 1950 they would have possessed at minimum
another 200 more and be laying down even more advanced ships as fast as they could come up with designs.
By mid-1943, the US Navy was already drawing down construction because they had already crushed the Imperial Japanese Navy so hard that it was just a matter of time before their defeat; the US Navy could have begun a soft pivot to the Atlantic around then, sending a majority of new construction ships to the Atlantic instead of the Pacific, and not lost any real effectiveness in the Pacific theater.
This, incidentally, is also ignoring the fact that the Axis (excluding Japan) didn't even have enough manpower nor hulls to counter the UK alone on the seas.
As far as naval operations go, Sea Lion was pretty much the picture of an impossibility - even if
Germany had actually possessed the warships they envisioned they would need at the time they believed they would need them. Never mind the fact they still didn't have the shipbuilders nor slipways to get them even that
...And before anyone says it, no, stepping up u-boat operations earlier would not have helped.
The U-boat was nowhere near as effective in starving the UK of sea-going trade as many love to insist, in fact in the grand scheme it made hardly any real impact. It hurt the UK's bottom line, sure, but in terms of actual goods and materials enough made it through that it wasn't even a quarter the way to a decisive blow. If the Kriegsmarine had stepped up U-boat operations sooner, all that would end up happening is the UK would more quickly develop the counters they already historically would.