Not quite the same, but I do think that short, frequently-stopping routes should be converted to light rail where there is potential to improve the service by doing so. This could take the form of Oldham-style diversions onto the street to get rail into town centres where the current station is awkwardly positioned, a frequency increase, or simply being able to modernise/electrify more cost-effectively. There is no point in having the prestige some people associate with a heavy rail service if it's worse at actually providing public transport than light rail would be along a similar alignment.
Obviously the fares should be integrated with both mainline rail and local buses if this happens.
I would say, on the contrary, that railway lines in this country should not be converted to bus routes, because even where that would on paper be better, it would be ruined because in Britain we simply don't know, and refuse to learn, how to run a bus service properly. Lack of timetable or fare integration with other modes, lack of live information, poor reliability, low-quality vehicles... the list goes on.