Time to move on
I know, it may be premature, but the mounting evidence does seem to say
that Mars was never "nice" long enough to develop any kind of life. There
may be nothing more than some microbe sized fossils, and those will take
a long time to find on a world with the same land area as Earth.
Let's start looking at more promising locales, like Europa, and of course
ramp up our SETI efforts. Those need to be aimed at different areas than
the usual traditional suspects as well.