Sir, it is the same situation as the one who is traveling with E-ticket(Have SMS but not having the printed ticket).
If PRS are about to discontinue Papers then it is the only way!!
What else can be done is just attach their PNR with their Adhaar or ID card!! and the checker standing at station to check the ticket of deboarding Passenger must having a device to check that is ticket linked to that adhaar no or not!! in that case peoples have to carry Adhaar letters only!! :)