It would give those precision landing competitions a practical objective... when I told my wife about the idea she figured that you would have to land on the train tracks. Can you land with the nosewheels straddling the centre line? Good as a starting point, a little more practice required.
You don't get passengers trains that convert to buses
It has been done:
E&WJR and SMJ - Locomotives and Rolling Stock: The Ro-Railer undergoing fare-paying trials on the route between Blisworth, Stratford upon Avon and the Welcombe Hotel . In the 1930s the LMS railway briefly tried a bus that converted, in Stratford on Avon. It didn't last long though.