If AMD / Nvidia see them as a serious threat they wouldn't be ignoring them.
Intel's GPU's have lower performance per transistor compared with out going generations, we are having to assume Intel fixed all of their problems, that their performance claim are true and scale across all game, not just the ones Intel selected, and assume people will give Intel the benefit of the doubt and buy unproven products over the establishment.
That is a lot of mental gymnastics we have to go through before we can agree Intel would sell them in any amounts that AMD / Nvidia would even notice. If they do do you think they will just sit on their hands watching it happen? No they will dump something on the market that completely kills ARC stone dead, AMD / Nvidia aren't going to let Intel gain any traction and unlike Intel they can do that without losing any money, right now some are doing loops in their head to convince themselves better GPU's for the same or less money don't already exist.
PS: Intel know this.... its why its effectively dead, because they can't fight that off and they know it.