but it can be a full time job unless it supported with other bitcoin activity like trading or mining
I dont think it is good to have a signature campaign + trading + mining as a full time job. Although someone can earn much from those activities, but all are something that not profitable all the time. Signature campaign may disappear anytime, trading may give negative profit, and mining is not profitable anymore imho.
I doubt about it maybe it can be a good job to gain nice profits but I really do not know if that is true, it has a good future and there will be some people that are gonna take the risks to do this for sure.
I even think there are already people doing this because the fact is that there are a lot of nice things about it.
First at all you can do it by yourself and second its very easy to do if you know what you are doing.