I believe the main drivers would be:

1. Give me a laptop that you can ASSURE ME runs linux amazingly well and in which I can instantly feel has the polish of mac hardware. I'm talking battery life, the amazing feeling of the butterfly keyboard, the trackpad (and respective software to enable it), the solidity of the device and overall ergonomics. Give me "Retina" HiDPI displays! This is definitely one of the top reasons holding me back: I don't want to purchase something and regret later because hardware support only "seemed to work, but actually really didn't".

2. Show me an operating system where things visibly work in an integrated fashion. I can drag and drop most things to most places. Progress bars exist and mostly make sense. All that jazz.

3. Make HiDPI work. I sometimes use a mix of heterogeneous displays, up to 4 at the same time. Some of these are widecreen, others are not. Some of these are HiDPI, some of them aren't. Some are connected via Airplay! The mac works amazingly well with all of them. Whenever I plug Linux onto these displays, something goes wrong. Things don't scale right. Everything feels slightly off. It's a nightmare!

4. Give me a VM solution with the incredible polish of Parallels Desktop. Perhaps these already exist, as I'll admit I don't tinker with VMs on linux often. Parallels Desktop changed my perception of what a VM can be, due to its amazing integration between the host and the guest. Applications usually just work, even in what they call "coherence" mode. Sure, linux guests sometimes misbehave, but Windows works like magic. I can drag and drop files between windows in the host and guest operating systems. I share clipboards. Windows from one OS appear in my taskbar as if they were native. I can very quickly enable passthrough on one device so it's in the guest instead of the host. I can easily setup different kinds of networks. This is INCREDIBLE technology that makes my life immensely easier either for work reasons (e.g. that weird chinese QR Code reader that only has software for windows, and therefore I set it up through passthrough) or just to chill and play some games -- actual, 3D accelerated games that run great, often better than their native versions on the mac (which is rather sad, sure).

5. Lastly, I am definitely very invested in the Apple ecosystem at the moment, and quite locked into it. I have over 5000 photos in the iCloud photos. I own an iPhone, Apple Watch, and Airpods Pro that I use daily (I own other versions of these accessories). I love the integration between all of these things. The way Airpods magically switch from one device to the other. The way that I copy paste from one device to the other (something which I use extremely often). I am definitely in severe vendor lock-in, and if I were to switch to Linux, I would have to deal with missing out on some of these things -- the Linux experience would need to be better than that of the mac, not just equally good (or "cheaper"). I don't really have many gripes with the mac -- as a developer, project manager, casual user, browser of the web, occasional writer, casual gamer, etc.

I guess, then, that Linux would have to blow me away with its integration and some kind of surprising set of features which I haven't seen yet. If it doesn't do that, then I have no reason to jump. I'm happily tied to the Apple ecosystem, and have no big complaints about anything other than the obvious fact that quality has been clearly going down -- but is still far, far, far ahead of my Linux experiences.