I tend to agree with some of the others here, don't worry! I was just at a friends house watching his ~60" 4k. It really didn't look crisper or sharper than my 1080, even when he was playing 4k content. Our rooms are setup about the same with what I would call a typical living room viewing distance. The effect is similar to watching a 720 32-40" tv vs. 1080; if you're pixel peeping you might notice a difference. In fact, some of the well done old tv shows like Hogan's Heroes look HD on my 42" 1080, even up close. Now, it's clear they're not HD on my 1080 60. Though it still looks better than most old stuff.
The color content with the 4k video, a video made to show off HDR, looked a little better than it would on my 1080. Though, I didn't get to do a true side by side comparison.
My AVR and Roku are 4k and support 1080 even with 4k content just fine. If I needed a tv, at the current price point I would definitely go 4k. No doubt. OTOH, with the current content available, I'm not going to rush out and get a 4k. 8k isn't even on my radar screen and unless they add some new trick (HDR+???) I doubt it will be until that's all that's available and I'm in need of a new tv.