My 2017 MacBook pro is definitely my last Apple laptop because it's just too expensive and unreliable (for reasons well discussed on HN). I have definitely considered getting a Mac Mini, but the new iMacs are definitely interesting. One thing I'd be concerned about is cooling. I know the iMac Pros are not ideal from a cooling perspective - I can't imagine an 8 core processor @ 5GHz plus a Radeon Pro GPU runs cool. I'll wait for the user-upgradable Mac Pro before I make a decision.
It won't be cool. It'll throttle. 9900K requires very good cooling, preferably water cooling to keep that 5 GHz and there's no way to put that cooling, especially along GPU into tiny iMac. Also I'm afraid that constant heating would damage some electronical components after few years.
I was in a similar situation in late 2017 and ended up getting a 5K iMac since I didn't need portability anymore. Best Mac I've ever had.
The 5K iMac couldn't cool the i7 7700K properly, and since fan noise is extremely annoying for me I got the i5 6500K model. In over a year I've heard the fan a couple of times, but it is silent most of the time. Performance wise, I've never found myself wishing I had gotten the i7. I do mostly dev, but also video editing, photography, and music production as hobbies. Of course I got the SSD and 16GB.
I've been saying for 10 years, that I am going to switch from a Mac to a ThinkPad running Linux. Yet I keep buying Macs. My latest was a MacBook Air. It really wasn't that much more than the ThinkPad I was looking at.
Their steps backward in MacBook functionality (keyboard, ports, touchbar which is at best a wash) and the price hikes over the last ~4yrs have me thinking about going back to Linux. But I need a laptop, and don't want to feel like I have to have a mouse to use it and not be miserable. And good battery life, and power management so reliable I never have to think about it (close the lid, pick it up, walk off). They're so far ahead of everyone else it's hard to justify switching even when they keep screwing up and raising prices for years. It's more a testament to how bad every other hardware+software combo is, at this point, than how good they are.