The most interesting result would be to discover that Mars life is unrelated to Earth life. In that case, the universe is probably overflowing with variety of life in every suitable niche.
Or perhaps we'll keep searching for a thousand years and never find a trace beyond Earth. In that case life may be exceptionally rare.
If we find evidence of current/past life on Mars, what is the math that this means there's "overflowing" life throughout the universe?
And of course, the inverse: If there is no evidence on Mars, what does this show whether there is no current/former life outside the inner solar system (besides Earth)?
Maybe we spend less on Mars (at least for now)? So much more out there than ancient lakes?
If life on Mars is related to life on Earth, that doesn't tell us very much.
If it's not related to life on Earth, then that means life can arise easily, so we should expect to find a lot more examples. Currently any instance of life is guaranteed to find at least 1 example (itself), so moving from 1 to 2 is significant.
> If there is no evidence on Mars, what does this show whether there is no current/former life outside the inner solar system
Evidence for the "Earth is special" hypothesis gets stronger the harder we look and find nothing, but we can never know for sure. At this point, we've hardly looked anywhere.