Oh wow that’s a bummer, I did not know that happened.
This post might just be my new personal record for longest ramble post
This is a fascinating topic to me as a fan of Lego as a whole. First off I would agree with @LegoDavid and all the statements so far, Lego is too far gone to go back now. AFOLs can spend more money and time on Lego so TLG will keep investing money into said market and yes that means more licensed sets banking on nostalgia or mainstream pop culture and movements and more expensive sets.
As a collector of vintage Lego however, to say “return to it’s roots” is different than what @thewimpykid says when he mentions Atlantis etc. I grew up with both 80s and 2000s Lego so I feel like I can speak of those two “roots.” And what it would entail attempting to return.
The 80s was simple. Town, it appealed to girls and boys, no emphasis on cars or emergency services. Plenty of house sets, a pretty steady flow of diverse set ideas and the Idea books showcase the potential of Lego at the time.
Space was simple exploration, no guns, only flashlights and video cameras and sets with probes, laboratories and mining equipment. Later space developed factions but initially there was no baddie barring aesthetics *cough Blacktron but still no story has handed to you initially.
Castle is an interesting one as it’s inherent conflict was the first blurring of Lego’s values, however it still had no particular goodie or baddie and had several neutral sets. Endless play potential.
Pirates when it came along was controversial having guns, artillery and well, being about criminals on the high seas. Still it was another theme with diverse play potential.
Now, into the later 2000s circa 2005 the same archetypes are repeated with perhaps more emphasis on conflict and the first forays into licensing with Spider Man and Batman etc. I love Mars Mission, Power Miners, Dino Attack, Atlantis, Aqua Raiders, Space Police III, Fantasy Era Castle, Knights Kingdom, all of that stuff. But we did see a gradual progression of simple more grounded themes not doing persisting. Less children relate to space as “We’ve grown use to wonders in our century” space is no longer interesting, castle and pirate the same. Why? Perhaps juniorising of these subjects, Pirates is a shocker as it is perceived as a little kid idea but is a fairly brutal piece of history. Yet it has become ordinary and boring. Castle, many cannot relate to and why bother when a video game can hand a detailed story to you? Lastly Space has become ordinary as we’ve remained grounded, with progress being slow in said frontier and once again why care about science and exploring when you can have a plethora of video games that provide immersive worlds and instant gratification along with conflict?
So Lego cannot return to the simple “create your own story, build anything with what you have” idea as the internet and video games is it’s primary competition. That is basically the point of this ramble. I love Minecraft and to a lesser extent Roblox, those two games fill the same space Lego inhabited for many kids. Roblox is free and offers a catalogue of games and Minecraft for the cost of one moderate sized Lego set has a infinite world with action and creative potential. And both of those games offer social opportunities and story telling scenarios. When compared with these or other games, Lego does not have much of a one up over them.
Lego, is not a story telling company, Bionicle and Ninjago are exceptions that they got lucky with thanks to exceptional hired people. They rely on their iconic status at this point, that people will buy Lego because it is a Lego, it is a rite of passage for a child to own some Lego. I’ve observed second hand Lego being sold and there is an increasing trend for children to grow out of Lego by age eight. I see bulk lots with sets from 2019 being sold. So Lego is going to go with what sells and they found Space, Castle, Pirates and even more mundane City sets to not sell. It may have been partly flawed execution on their part with the last examples of each range being rather dull but it has driven them to go with what works whether that be brands like Marvel or the evergreen Ninjago with it’s motifs borrowed from all those dead ranges.
So can Lego return to its roots?
One cannot be absolutely certain but if we look at events after 2014 I think it will not be returning to it’s “roots” any time soon. Children seem not interested in “make your own story” type mediums or at least ones which they cannot experience first person. Afols will continue to buy big sets and licensing, we will continue to get a steady flow of tribute sets to the themes of the past but little more than that I think. Lego will lean more into the hipster nerd market and grab more licenses. Kids growing up now are simply already invested in established stories like marvel not a simple story like Atlantis or Power Miners. Those 2 to 3 year themes can hold some children’s attention and can be somewhat successful but it is a lot of effort to design a new range and cycle through them. They could go back there if they really wanted. But they will wait for something to break before they go back that formula. Another thing which they can still do is make City appealing to a broader group, they can still move the emphasis from emergency services and vehicles. I believe that would be a successful move. So City can return to it’s roots but the other themes are much less likely.
Once again the future is not clear so perhaps they will try another Chima or Nexo Knights and it will stand next to Ninjago for a time being.
for those who read this entire disjointed ramble of my nostalgia blinded self! 
) don’t buy LEGO because they appreciate the deep story and unique ideas. They buy them because they want to play with the samurai mechs and ninja cars, or they want to play with their favorite superheroes that they saw in theaters.