The electric air taxi business—spurred along for years by Uber’s Elevate initiative and also known as flying cars—is flying into a cloudy unknown: The murky pall of the Covid-19 pandemic and its related, brutal economic downturn. Given how plummeting revenues and homebound consumers have gut punched the established airline and automotive industries, it’s easy to lose all hope for a newcomer that requires an especially long runway to take off.For certain, some players chasing the urban aviation dream won’t last long. With 250 companies working in some capacity on the…