Well, 4:3 HD projectors do exist, & a plus to having a 4:3 projector is you can always fit an anamorphic lens on the projector to change the aspect ratio to flat 1:85:1, and any CinemaScope ratio, & still be able to watch native 4:3 content ( such as TV shows shot in the 4:3 Aspect Ratio from the 50's to the late 90's (until producers started filming in the 16:9 aspect ratio) without having black bars at the side of the image.
I wish that a manufacturer still made 4:3 HDTV's ( they were made in the late 90's to about 2004-05)
I almost bought one, It was a Phillips Projection HDTV 4:3 around 2002. I had just replaced my 1989 Pioneer Projection TV with a Phillips projector back in 2001 then the next year I saw what looked to be the Identical set except it was HD, It was open box and I could of gotten it for $400. But I could not bring myself to buy a new TV when mine was working fine. There were many 4:3 HD Projection sets early on and there were some Hi Def CRTs too. I still prefer CRTs to LCD and Plasma. Pictures were Brighter and sharper. But the some of the new 4K sets are now getting there.
yeah, the new 4k sets look really good, the Samsung SUHD nano crystal tv's & the LG OLED tv's are ones I have my eyes on.
If LG or Samsung could make a 4:3 OLED or Nano-crystal LED, I believe that it would sell fairly well (mostly to Graphics & Imaging Industry, & Post Production houses)
Samsung makes Cinemascope TV's (Ultrawide Series), so I think that they could make a 4:3 set with no problem