"Currently, there are five dateable characters, and I hope to add more down the line." doesn't "more" imply more than one additional route? If it were just one surely it would be "another"?
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While you are correct about the implications of that phrasing, subsequent comments from the author seem to indicate that Richard will be the only one. (Probably because as you point out, Richard is basically the only character available without writing in an entirely new one, which would be a giant pile of work.)