We're now seeing examples where DNA can be built using arsenic.
We're now seeing examples where DNA can be contaminated with arsenic. Fixed that for ya,
The public's attention for exoplanets is already waning.
One day I expect Kepler to discover an Earth-like planet with an Earth-like atmosphere and the public won't even care. Getting funding to image the surface of that planet will be an uphill battle and even if the returned images show undoubted proof of intelligent life, people still won't care.
Can you imagine that?