I had the Samsung JS9000, the previous generation flagship and a curved screen, but by all accounts quite similar in terms of picture quality to your KS7000. I switched to an LG OLED and yes there is an enormous difference. I didn't think it would be so noticeable. The biggest thing I noticed was the black levels and the difference between bright and dark areas of a scene. The KS7000 is edge-lit, as was my JS9000, and it just can't compete with the per-pixel dimming of OLED.
I have had my OLED for about a year now and I still get 'wow' moments watching UHD content. You'll get the best out of it if you buy a 4k blu-ray player, but 4k streaming content does a decent job as well. For example, 'Our Planet' on Netflix looks absolutely stunning on an OLED TV. Also, the UI and remote are way better on the LG OLEDs than the older Samsung UI. Samsung have improved that recently, but it was poor on the JS and KS series TVs. I was never really blown away by my Samsung TV, in retrospect it was a bit disappointing given how much I paid for it, but I don't regret one bit upgrading to OLED. I was lucky that mine was a free upgrade thanks to extended warranty after the Samsung broke and couldn't be repaired.