Interesting article in The Scotsman: https://www.scotsman.com/sport/football/teams/scotland/why-scotland-fans-are-wrong-to-look-to-croatia-as-a-model-to-follow-1-4767975
Basically says Croatia succeed despite having no plan or structure. However the players get first team football at an early age, come through U21s together and then have no fear leaving home. That said there has to be some luck involved when you get players if that quality at the same time. How many of England's team could play for Barcelona, Real Madrid, Juve etc?
Maybe there are things to be positive about. We just have to wait a little bit longer.