Whilst there is an element of the Monty Python 'trying telling kids today and they just won't believe you' the means of entertainment were fairly limited in those far off days.
All true - but fact is there are plenty of options for people to do other things. RL has to compete with plenty of alternatives both for kids playing and for spectators. The huge wedge of cash the RFL gets from Sports England suggests the govt recognises that getting kids playing RL is good for everybody.
It's not just RL that struggles to compete with soccer for kids attention. My youngest son is playing union. From what I see, a llot of kids playing union round Cambridge do so because they're basically too fat or too posh to play football. Clubs are not that close together either - we typically travel 30-45 minutes for away games to places like Harlow, Bury St. Edmunds, Braintree, Huntingdon. If a town the size of Widnes has 3 junior clubs, that is definitely a hotbed as far as most of the country is concerned.
RL has over 1000 people working full time in it - compared to maybe 30 (at most) in the 1970s. There's more people playing in the UK than there were in the 1970s and more people watching. That's a funny kind of dying.
I wonder if switching junior RL to summer would be a good move - much easier to practice skills, light in the evenings, no standing round freezing to death, no competition from soccer? Obviously you have a problem with holidays, but maybe it's the way to go?