I want to go a little smaller, ideally my 8 plus will be my last larger size variant phone. Once Touch ID returns, I'd be quite happy to drop down to a 5.8" now the battery life gap has been substantially shrunk. Having said that, if the 2020 iPhones really do drop from 5.8 to 5.4 I might have to reconsider my options. Going by the available 16:9 area, 5.8 gives you around 5.0" and 5.4 would give around 4.7". Previously I've had a Lumia 930 which had a 5.0" 16:9 screen, and I thought that was a real sweet spot. I don't know that I would want to go even down to 4.7".
If the size variants do change as rumoured, I might have to look at what compromises the 2020 6.1" OLED has - if it's anything to do with the screen (lower resolution or cheaper off the shelf diamond pentile layout) or if they omit the under screen Touch ID for cost savings that will also be an instant no for me. Sounds like whatever route I go I'm going to have to compromise on something...
I could get a 5.8" "XI" or a XR or "XIR"- but no Touch ID
I could get the 2020 5.4" - but it'd be a little too small at that size
I could get the 2020 6.1" - but I [might] have to compromise on the display quality, and it might not have Touch ID
I could get the 2020 6.7" - but it's no smaller (and possibly even bigger)