Undoubtedly, the US Navy would have fully grasped and expanded upon the ironclad as the new warship if the War of the Rebellion had lasted much longer than two years. The naval build up begun by Lincoln's administration was virtually gutted by the McClellan Administration which was swept into office by the victorious 'Little Napoleon'. One can see that General McClellan's crushing victory at the Battle of Antietam was the crowning achievement to his Peninsula Campaign, that witnessed the capture of Richmond, was entirely dependent upon the Union Army.
One can also only wonder what also would have made a difference if Ericsson's novel ironclad USS Monitor had not floundered on its way to Hampton Roads. Ericsson did go on to produce modified versions of his turreted shallow draft ironclad for his native Sweden and the vessels did figure prominently in the Greek War of Independence.
The few ironclads that the US Navy did build were predominantly improved versions of the USS New Ironsides. However, even the few broadside ironclads that were built were largely laid up by the 1870s. The US Navy returned primarily to its sail heritage until the 1890s. Many of the 'Lincoln Steamers' paddlewheelers quickly built and launched at the outbreak of the Rebellion remained on active service will into the 1880s, but usually in secondary roles.