Petition won't do any good, as there is no way those suits will revert to Wright with their bloated egos.
But getting the buzz through memes is a good idea to show support to Wright, as those are more prone to catch on. Ever since Whedon's photo tweet, I been thinking maybe fans can start posting photos of themselves with a Cornetto or photoshopped images of existing characters with a Cornetto or something to that effect.
But for many it's more about the brand (Marvel) rather than the people behind it like Wright, so not sure if it can really take off. I too have the loyalty towards Marvel Studios, but besides the characters it's these creative individuals is what I admire and cherish more.
What will really make it better now is if Universal announces a new movie with Wright directing it. They distributed all his prior movies and also produced Scott Pilgrim. And now with the backing of Legendary Pictures, Universal can truly get back into making more big budget films whether it is franchise films or original standalone genre films.