Only access the net via a Linux installed inside Win 7 as a virtual machine.
That's pretty much what I already do, so 2020 isn't going to matter to me. The only real difference from your proposition is I don't even bother with AV anymore. I just create a known-good VM snapshot, and every time I start the VM I start from that snapshot. That way, if anything bad did manage to get into the linux VM, it would get flushed out by the reset-to-snapshot at the start of each VM session anyway.
As I see it, the "linux-plus-WinVM" vs. "Win-plus-linuxVM" strategies each have their pros and cons.
In the "linux-plus-WinVM" scenario, what you're saying is you're going to commit your web browsing to the increasingly less secure of the two OSes, and you're going to be doing most of your non-web work in the host OS, linux, with it's attendant learning curves -- not just for linux, but inevitably for the new programs and applications you'll have to switch to, as well. I'm not sure that would be an attractive option for me. You don't want to continue doing your non-web work in Windows because you're also using it for the web ... and if you were to favor that route, then there was no point to setting up a VM in the first place.
In contrast, the "Win-plus-linuxVM" scenario means you're going to commit your web browsing to linux, an OS that not only should continue receiving security updates, but is also arguably a smaller target for attack to begin with. (I'm presuming the majority of malware attacks target Windows users.) You can also continue doing most of your non-web work in your old, familiar host OS (Windows), and with your familiar programs and utilities. The downside is your host OS will still have to be able to connect to the net in order for the VM to access the net. If you're never using a web browser in Windows, though, that risk will IMHO be acceptably small.
I'm already using the "Win-plus-linuxVM" strategy, and I don't plan to change anything in 2020. FTR, I also quit updating Windows at the end of 2017 when the Spectre debacle hit. So 2020 changes nothing because I've already quit updating Windows.
