"The People" have not been seen in Toobworld since 1972. To comprehend where the lives of "the People" might be today in Toobworld, we have to extrapolate from the material and clues to be found in the TV movie, with no regard to anything that might have been revealed in the writings of Zenna Henderson.
But for the moment, let's consider what Ms. Henderson suggested in her short stories.
Not all of the People landed in the American Southwest. Some of the life-ships could have landed in other areas of the planet. And we'll be considering such an enclave of survivors in the next post........
Elsewhere, a number of People were rounded up and burned alive by religious devotees who mistook them for witches; a colony formed by survivors seeks not only to conceal but to wipe out their powers, punishing children severely for any paranormal activity, in general replicating the lifestyle of the ironclad fundamentalists who murdered their ancestors.
Let's take one of the ideas suggested by Ms. Henderson in an unfilmed story:
Eventually, People from a colony world discover the People on Earth, and enable them to leave this planet and go to the "New Home," if they so choose.
This is the same premise I have in mind for the Tenctonese of 'Alien Nation'. It would certainly splain away why we haven't seen any Tenctonese in TV shows set in the general Los Angeles area since 'Alien Nation' and its TV movies sequels left the air. (I'm not a xenophobe, so I won't call them "Slags" or "Sponge-Heads".)
Here's another factoid to consider:
The People have significant control over their own metabolism, and even have the ability to alter themselves to adapt over time to new environments, which could also alter their appearance. Thus, the People who lived on Earth are not exactly the same as the People who lived on Home.
From the TARDIS Wiki:
The Krillitanes were able to take the abilities from other species, giving them new appearances and qualities. ('Doctor Who' - "School Reunion")
This makes me think that the People were once similar in body design to the original forms of the Krillitane. If not, their species may have shared a common ancestry out among the stars.