No ICL camera can compete with the RX10iv for single-lens convenience from 24-600mm equiv at any price. All the ICL choices require 2 lenses minimum and usually, that makes the choice as or more expensive than the RX10iv and a lot less convenient.
You wanna bet?
My last vacations i took with me a 18-140mm lens, big mistake.
The only site i used 18-35 mm was in the caves, at a certain point we switched cameras to have more range ( even for close ups i'm a minimum focus distance abuser).
I said to my father, next year i will come better prepared.
This year i'm planning to bring with me just one lens, a 100-400 mm minimum.
and a second camera just in case
You moved the goalpost. You have not demonstrated that any ICL can match the single lens convenience of the 24-600mm range of the RX10iv. While you might be able to be happy with 100-400 (150-600 on APS-C) I'll wager you are very rare in that regard.
I would be very happy with a long prime.
And you would lose. I'm used to have 720 mm, i found that a 18-140 while a good lens i found it short, i have no problem in dropping 100 mm. My average from photos it's 210 mm, so...
One lens to walk around.
And my G5x for caves and village festivities.
(fun fact, last year i spent two months seeing lens and lens review, i couldn't make my mind, so i decided to go on vacations and see what i would miss the most, after my vacations, my mind was clear about what i need the most).
What i pointed out was it can be debatable, nothing more.
A DSLR or Mirrorless with a super zoom will have the same convenience.
Either type of camera will have something to sway us in a direction or another.
I started with compacts but wen faced with an much heavier and bulkier setup (being a bridge camera or a DSLR or a Mirrorless) i decided to go for a DSLR, bigger sensor not that big of a difference in bulk or weight ( i mean, i can't pocket either of them).
Other factor made me choose and invest in my DSLR, i can point and shoot immediately.
- i can keep it always on ( much better battery life).
- reliable and fast AF
- It's always on my last used focal length
without any delay or waiting to turn on. such things didn't exist at that time, even today those "features" aren't that common in Mirrorless or compact..
I became a fan of OVFs, i'm snappier with them. On the flip side, i don't have as much "support" as you probably have. killer AF, a bucket load of FPS and other killer features.
In the end, it's choices. As i'm getting older i'm seem to prefer comfort of shooting