I have noticed that the Wiki Page for young Richard has been expanded considerably and now includes reference to his possible illegitimacy. It even provides us with an image of him, and to be honest I don't recall having seen it before, though I may have done somewhere.
What the article fails to mention is the seminal work of T.B. Pugh in Henry V and The Southampton Plot, which is unfortunate because I am 95% certain that Pugh was the first reputable historian to draw attention to the matter and suggest Richard was not born until 1385, or thereabouts. It also fails to mention that Shirley, the 15th century collector of poems and servant of various nobles, the man who first linked this supposed affair to Chaucer's poem, had known links to Isabel Countess of Essex (Cambridge's daughter) and Isabelle, Countess of Warwick (Cambridge's niece.) These ladies were in a position to know their family gossip - whether they shared it with Shirley and told him it was 100% kosher we shall never know.
Frankly I should prefer to think that Edward IV and Richard III were descendants of Edmund of Langley - but we can at least be reasonably sure that they were descended from Lionel of Clarence, which is they key thing from the point of view of the succession.