They always find a way:

Any discovery that would put the theists out of business would be welcomed.

It depends on the sect, but I can tell you that young earth creationists are busy turning themselves into young universe creationists. Which, when you think of it, is inevitable.

I was debating one of those guys on their own site once and made the offhand remark that we might find life on other worlds and he went ballistic. I never thought this would be a particular problem for them since the Bible doesn't even have a cosmology that contemplates the infinite universe we live in; it saw the heavens (the "firmament" ) as like an inverted dome in the sky, its edges resting on the "foundations of the earth", the stars simply lights attached to it somehow. So the Bible is silent about whether there is extraterrestrial life. The most you can say is that the earth is a special stage on which the drama of redemption plays out.

But this guy was having none of it, he firmly stated that any life found elsewhere in the solar system originated on earth. For some reason this was terribly important to him. They have a theory that the cataclysm of the Flood spewed all sorts of microbial life and organic materials into space and that if any life is found elsewhere it would have come from this in a sort of interplanetary panspermia.

Since then I've noted them talking about the telemetry coming back from Pluto and comets and claiming that the organic molecules on these are from Earth -- despite that for example the period of many bodies that visit the inner solar system is so great that they would be visiting the environs of earth for the first time in thousands of years, and so would be highly unlikely to be bearing these materials from earth (to put it charitably).

One thing the Bible does do is say that god created the heavens and so if these events happened 6 to 10 thousand years ago, the entire universe has to be young and created with "apparent age" or some such nonsense.

the film Paul says it all

We know that material transfer from Mars to Earth has happened. It can therefore be credibly argued that material transfer between any two bodies of the Solar System can happen. If mircobial life is found anywhere in the system beyond Earth, the next question will be, did it originate on Earth and transfer beyond, or the other way around? Hopefully, genetics and other analysis will have answers if we are in this situation. Another possibility is that we find exraterrestail life clearly different genetically from anything on Earth. That would strongly suggest multiple starting points for life and would be pretty strong stuff for knocking us off center stage in God's mind, by which I mean our opinion of ourselves.

It won't change a thing. The religious types will explain it all away. Think about it: the stars in the sky, some millions of liht years away, refute the creationist idea that the entire univese is ubder 10,000 years old. If they can explain that away, life on other planets would be a snap.

They will figure out a way to make it fit with their beliefs. Maybe Ken Ham will make a Titan Ark?