Okay, so I don't know if anyone's discussed this yet, but...
Remember Princess Romelle from the 80's? Allura's doppelganger from their sister planet Pollux? Who else hopes she makes some kind of return in Legendary Defender?
Here's how I think it would go... Soooo maybe, before the destruction of Altea, there were some space exploration teams sent to uncover the far reaches of the universe. The discovered a planet capable of sustaining life, but without any sentient beings currently abiding there due to insufficient evolution. They decided to report back to their superiors... Only to learn (somehow) that Altea was destroyed and they no longer had a world to return to. The Altean crew decides to start their lives anew on the strange new planet they eventually name "Pollux*.
Ten thousand years later, the Polluxians have only recently been noticed by the Galra due to the fact that they had to reestablish their entire civilization, and did not have any noteworthy resources until now. The battle for the planet is ongoing, with the Polluxians slowly losing. Until Voltron shows up! An alliance is formed, we get some character development for Allura (" more...Alteans?") and for... Well, if you've seen the 80's version, you'll know what I'm talking about😉