No, he was not. For Marconi, wireless transmission of information was just a byproduct of the far more important wireless transmission of power. In the linked text he is explicitly distinguishing his idea from the mere wireless transmission of information with electric waves which are quickly damped out.
Yes, he was completely wrong about that.
And ubiquitous wireless communication was a widespread idea at the time, here is an example from 1897:
http://www.citizenarcane.com/index.php/archives/2005/03/28/e...