It would be easier to change humans to be something that could live comfortably on Mars than it would be to make Mars that is comfortable for humans. If Mars is ever really permanently colonized it won't be by "us" as we are now, but maybe something like us.
In a similar way I could see something we make traveling out of the solar system, maybe we could even seed life. But it would be something different than us.
In a similar way I could see something we make traveling out of the solar system, maybe we could even seed life. But it would be something different than us.