I think the ideal would be to Ennis-ise the line, by which I mean divide the line into two with the Killonan-Nenagh stretch which has had substantial spending on it finished off - track stressing, LC automation and a single railcar shuttling up and back or running through from Ennis on a 2-hourly timetable with journey time more like 40mins than the current 55.
It seems to me that the money to bring the track north of Nenagh to mainline standard isn't there, but a heritage operation along the lines of the
York-Durham Heritage Railway could keep things going on an engineers siding basis between Nenagh and Roscrea to keep the line in good nick at volunteer/sponsor expense - those are decent sized towns which could draw on a deeper pool of support than the villages along the South Wexford line. Perhaps in the future a properly run shuttle would draw enough business to contemplete restoring the shuttle to Roscrea or further without yanking trees out of the alignment as in the case of Midleton.