Thing is, why would the kid have dark features? not even an ounce of white/light hair or pale skin that nikka a whore's b*stard, no pure Targ blood in him.
there's precedence for that. rhaegar's daughter with elia martell was said to look more like the martells. danarys and viserys and rhaegar all had the targ look cause their mother and father were brother and sister but whenever targaryens branched out their look would always fade a little. thats why they liked to inbreed to keep the bloodlines pure. there was also a targaryen way back called baelor breakspear who looked dornish cause he also had a dornish mother or father. also they make a big deal about how jon and arya are the only 2 of ned's kids that look like starks and then everybody says arya looks just like lyanna stark.
i guess now that the cat is out of the bag, yea a huge percentage of book readers believe jon is rhaegar and lyanna's son but it isnt confirmed. there are also people who believe he is the son of ned and like 3 other women who are named and some believe he is lyanna and rhaegars son but that she was raped. shyt theres a forum called westeros.org and they have 77 ongoing threads about jon's parentage so that goes to show u how nobody still knows anything for sure.