I really don't want to be pessimistic, but considering that MEAction has gathered around 20,000 signatures in other actions - as far as I know over a longer period than 4 weeks? and with better social networking? - I see little chance that this creates 50,000.
When I look at some of the comments, I feel hopeless, because they show "the bigger problem", which is not so easy to fight against (and which is not limited to ME, although I have the impression that there is a lot of prejudice against ME).