While I would hate to enable upgrade-itis and run counter to the theme of the thread, HDMI has data-rate limits and not resolution limits (well it does have those too, but we're not running into them here). Typical film content (4K 24fps) uses less throughput than you'd think, and there's a real chance a within-spec HDMI 1.4 era cable could do 4K 24/30fps with full 10-bit per colour.
Unless of course you've already tried this and it didn't work and thats why you say it only handles 1080p.
I want to chime in regarding the practicality of home theatre in a room that is not dedicated (living room) and why this thread is I think resonate the basic thing that most of us seek, and eventually have to always compromise. And some compromise could turnout to be acceptable
I use Apple TV4K as source, to Denon 1700 , to an LG TV (from circa 2016), in my living room setup.
I move The previously use HK5550 to my study for two reasons
1. The remote has become less responsive in some buttons
2. I want to try Atmos (5.1.2)
All working just fine, although I still prefer Logic7 for up-mixing,
the simplicity of using just Apple TV4k remote to power on/off and control the volume and browse the source, turns-out make the system way more utilized by my wife and kids.
Since
the room is open concept (non-symmetrical side walls); I have three options:
1. Put the couch in 2/3 of room length, 5.1.2 - ideal.
2. put the couch against the rear wall, use 7.1 but the side surround is closer to front (between 45-55). [For music, I like it better. For movies, I don't think I miss that much, comparing, and not having height channel, so long as the surround channels put bit higher].
3. Put the couch against the rear wall, 5.1.2.
My other family members enjoy "something coming from above" better. And they prefer this setup since the more spaces between the TV and the couch gives the flexibility to do
multi-tasking: play board games while enjoying music, could do group Yoga/Aerobic using more space between the couch and TV, plus study group discussing some slides / presentation rehearsals using Apple TV4K displaying content from iPad. And the way this room is utilized to become more
Communal, (I prefer kids nowadays hanging around at some living room of some home with some adults / parents around, hence, my house become sort of "basecamps" for my daughters, compared to let them don't-know-where doing don't-know-what), I think that, plus I could get to know the friends of my kids, learning new things from them, as well sharing some good music from my era and theirs, that's something that I prefer.
When everyone is not home, I back to #1, set to another audio preset for that position: done.
Now, being able to do this, I once tried to get some projector, but my wife
hesitated to since our previous experience (the fan noise, the durability, the more complicated setup, the cost) had not been so good. And though I really do want to put center channel behind some perforated screen, but if the setup only cause my other family members to not using the setup since she thinking about the working hours of the projector all the time; then we could just go back to TV.
Now I've been thinking about UST Projector, (albeit still no center channel behind screen), but HDMI connection could not just make my stable output for PS4 through the AVR to my TV, (the fact that maybe my TV is to old for the HDCP), but still I just can't justify the purchase due to the potential issues comparing back then when the Video Cable are separated from Audio Cable.
And since the kids nowadays don't really care whether the sound is coming from TV to AVR - Multichannel up-mix vs 7.1 direct connection to the AVR so long as they play together with their friend, and that using more modern TV I could just alternate the connection with shorter cables, we
compromise with no projector.
If somehow No HDMI problems like we encounters like now, I would get the biggest screen + Projector knowing that the only problem I might encounter is just to "replace the lamp". Now seems everything is in the edge of software vs hardware compatibility. The thought of trying every cable that just works, hide them neatly, then introduce to the same problem once another electronics is change/added, or even worse, after merely software/firmware updated, make me hesitant, since to me this entertainment systems should be just an oasis with acceptable compromise, never should just be another source of avoidable nuisance.