Once BR was broken up, the genie was out of the bottle.
Freight and rolling stock are in private hands.
The infrastructure is now back in public hands after the Railtrack/NR privatisation experiments.
The passenger railway never actually left public control, even if delivery is contracted out.
Looking back BR was an incredibly introspective outfit, and could do much as it liked within its (tough) spending limits.
Nobody got to review its plans and have their say.
Nowadays every single aspect of operation is consulted on, fought for/against, funding sought and spend monitored, including the fares structure and punctuality figures.
When was BR hauled in front of the Transport Select Committee and given a mauling?
Did they ever produce 5-year Business Plans and 25-year Route Studies for public consumption?
What would have been their equivalent to the recent Northern/TPE franchising process?
Looking ahead, devolution is rampant, with the possibility of the railway being split into many more pieces.
New lines are being built outside the "BR" envelope (Heathrow, Crossrail, HS1/2/3), with extensive external funding.
Open Access will stay.
The genie is not going back in the bottle, even under Corbynrail.