It isn't that there are not new to EQ players still coming, but the cost of a good advertising campaign today with EQ being EQ, is not going to garner enough support to pay for the advertising campaign. Now back when EQ was still fully subscription based game or when it had just went F2P, then such a campaign would have be great. Today, I just don't know that the investment would be returned in a way to make it worth the cost.
Old School Runescape really became successful due to its mobile launch. I don't think we'll be seeing Everquest Classic on mobile any time soon.