We'll have to wait for the embargo on how this works exactly to end, which is supposed to be soon. There are a lot of unknowns, which CPU's exactly, I heard all produced in the last 10 years. Is it just in 64 bit mode? And such.
I can't talk for Arca Noae, but I doubt that they're capable of patching this, it's not like they have the kernels source. The OS4 kernel could be patched.
Anyways, in many ways our platform is insecure to begin with. We're always at least a year behind in browsers, which means security holes and the possibility that one tab is spying on another. Things aren't sandboxed, especially the browser, which is our biggest security hole.
On the other hand, I doubt that many people will be writing code to use against the few OS/2 users, there are much better targets. The NSA may be able to log into the Intel management engine or the AMD equivalent and basically run software at ring -1 with complete access to the computer and sooner or later someone else is going to use the same backdoor.
There's also the question of whether this flaw really affects OS/2 as I believe the kernel memory runs in a separate segment, something that is not supported by 64bit mode and I believe gives some protection.