It's a bit more complex than that. It happens for both TW1 and TW2, for different reasons. TW1 was an excellent game crippled with bugs, due to CDPR being by then a serious company with limited resources. Releasing TW1 EE washed out most bugs, making it a great game without caveat.
TW2 EE only came because the success of TW2 on PC made CDPR willing to invest the console market, which is known for being, to say the least, different. Because they got the investment to do that, they got the investment to polish the original game, add a bit of content, and get away with it. Free goodies for PC players. Divinity Original Sin did exactly the same.
TW3 doesn't need an EE for anyone but die hard fans. It's a GOTY game already, praised by all media, and is considered by many people one of the greatest CRPG of all times. It proudly sits along with Baldur's Gate 2, Planescape Torment and Fallout series pre Bethesda. You cannot enhance much out of such a success.
Thus, an Enhanced Edition, from a pure development perspective, would be a waste of money. All in all, people wanting an EE are just people who doesn't like some choices made by CDPR, or who wants "the E3 demo !!!" or you want some advanced mods.
So yeah, I don't see that happening easily. Fresh investment from fans may make it happen. I personally believe a more advance mod tool, along with a better, less selfish modding community (which is currently quite self centered, and obsessed by their own glory, and would rather keep their secrets to get this extra endorsement rather than seeing a more talented guy do better than them and improve the whole game in the process - rare are the KNG, CVAX or Chickenodum free sharing their work) would do that more efficiently.
I wish CDPR would prove me wrong, and do like they have done since the start : surprise us with ever more polished game, and never stopping short of perfection, but The Witcher world is currently on pause for them, and they are already focusing on their next project, and that's fair enough.