"The interurbans completely vanished", is what the various railfan books and publications typically would have us believing. It is true, that there were generally no alternative public transportation options introduced, after the Chicago Aurora & Elgin and the North Shore Line shut down. Passengers either began driving instead, or switched to the paralleling Chicago & North Western Railroad.
But for the more typical local interurban lines, many of those companies did not simply abandon the electric railways and disappear. But instead operated replacement bus service. Many railfans of course resent buses, with various conspiracies over the years such as with National City Lines. Interurban railways may be interesting to experience, but in reality became impractical only 20 or 30 years after they were first developed.
What happened to the interurban bus companies? The companies were gradually acquired by Greyhound, which eventually consolidated them into the nationwide Greyhound Lines bus system. In the early days, those interurban bus lines continued to provide local service, as did the interurban railways. But those local services eventually became unprofitable. The real tragedy with interurban transportation, is that almost none of the areas served saw it fit, to create public transit districts to enable preservation of local interurban bus service. And in the 1980's, when deregulation of the intercity bus industry enabled Greyhound to discontinue unprofitable services, residents of smaller towns were left with little choice but to drive.
Greyhound's focus meanwhile moved to longer distance express bus service, travelling on Interstate highways and stopping only at the most important cities. Providing services which would be more appropriately provided by an intercity rail passenger system.
Meanwhile, in most areas of Europe, interurban bus routes continue to connect the various towns. Some bus routes created new, other bus routes having evolved from interurban railways. And a few interurban railways continue to exist. Could such an interurban system work in America? Only if the many communities in a region are able to all work together, and agree that there must be an alternative available to driving.