Problem with the end (spoiler)

First of all, let me start off by stating that this movie isn't a poor man's version of the Thing...its a dirt poor man's version.

...but Bruce Campbell is in it, so that earns it big points in my book.

Anyways, didn't the alien at the end say that they stumbled apon a training session and that their race of aliens had plans to make the people of Earth their slaves?

So they killed the 4 or 5 aliens training...but isn't Earth still screwed? Unless they change their mind because Earthlings are stronger than they thought they were.