A report about French financial railway sustainability from Mr. Jean-Cyril Spinetta landed 15.2. 2018 on the table of the French government.
The report carries many interesting observations. The lack of money (automatic state subsidies are gone) is eminent. Like in Japan back in the 1970th. they could stowe away the accumulate debt in a separate body!
It is clear, that a lot of minor lines with little traffic are costly, and the even need much more repair! It is also clear that HSR is better of on the most profitable lines, but not everywhere. And how can trains be competitive to airlines with the existing cost structures talking about more than 3-4 hours ride on rail? It is here the night trains are relevant.
>> See the full report here (in French)
Observer and blogger Alon Levy has studied the report, and has made an English summary hére.