Marvel's Eternals franchise has revealed a pretty tragic connection to Shang-Chi and the Legend of the Ten Rings – a connection that has been established by Marvel itself. A WEBTOON comic book tie-in to the Eternals movie called Eternals: The 500 Year War has been launched on the Marvel Unlimited digital comics subscription service; issue #6 of Eternals: The 500 Year War features a story of Ikaris and Sersi battling a Deviant in 16th century China. It's that story that provides the best insight yet as to why fantastical creatures like dragons – and realms like Ta Lo – are no longer connected to the MCU.
Yifan Jiang's story of The Eternals trying to defend an ancient dragon from a Deviant is just a small example of what we learned in the Eternals film, concerning the history of the Eternals-Deviants war that has raged on Earth. Admittedly, Eternals didn't do all that great of a job distinguishing the Deviants as villains or explaining (beyond abstract exposition) why their wildly evolving DNA makes them so dangerous (resulting in a being like Kro).
So, it seems like Star Wars, Marvel is now using its other media platforms to fill in some gaps and sure up the connections in its shared universe. Marvel is effectively using the Eternals and Deviants to help explain why the wonders of ancient Asia faded from the modern world (but left behind their legends as stories, as told in Shang-Chi). The web comic's story also includes the Doctor Strange franchise in the mix, by having one sorcerer protector of the ancient Hong Kong Sanctum be the one who also tried to defend the dragon against the Deviant.
Any way that Marvel can find to tie the Eternals and their history more closely to the rest of the MCU franchise is a step in a better direction. While Chloe Zhao's film got a fair amount of praise for being such a standalone departure from the usual MCU movie formula, it also had some stumbles trying to find the kind of resonance that most MCU movies have with fans.
That all said, Eternals: The 500 Year War is solid enough proof that there's still a lot of open room in the future of MCU storytelling to hop back through history and let the characters of Eternals (and/or the cast) star in their own standalone or collective stories, detailing key influences or pivot points in MCU history.
You can read Eternals: The 500 Year Wars on the Marvel Unlimited App.