Just to clarify, HN is written in Arc, a Lisp variant, and (purely incidentally) runs on FreeBSD. As the sibling replier noted, SAFE appears to be hosting-provider-specific.
Also, I'm definitely not OP, but since I'm here, and just in case...
My own knee-jerk reaction goes straight to the value proposition of the cloud vendor it's tied to, which is a very odd/unusual dimension to bring to a programming stack (eg, LAMP isn't tied to Windows, or to GCP, it's entirely neutral). Cloud vs bare-metal vs VPS vs virtual hosting vs etc all have different cost dimensions and optimalities. Given that I can run PHP on App Engine, GCP, and (with a small amount of existential screaming) random Web hosts... PHP is canonically a bit more flexible than SAFE. (Then you've got the argument of "but you can technically run SAFE elsewhere" - to which I respond "okay make the A mean something else then!")
As for my generic opinion on the rest, it's all about what it brings to the table. If it introduces something genuinely new that adds a bit of "essence of 10x", if you will, if that new thing is tied to the rest of the stack, and the stack gets out of people's way to enable that 10x thing, then yeah, the stack'll follow after the new thing and catch on in the process. Thing is, "getting out of the way" is the critical part that is so easily gotten wrong - if you're trying to show people new ways of doing things, and it just feels like how they were doing things before, it doesn't matter if they look different, the magic just falls apart, and the new thing won't catch on. IOW, in much the same way that successful existing products are a million tiny details gotten right, successful visions for new things are those same million tiny details from the perspective of the new thing that doesn't "exist" yet. Does this do that?
Secondly, regarding your curiosity about whether this thing will languish and die... for what reasons might that be especially important? For the sake of debate, I'm not presuming you're actually coming from that perspective, I'm asking what if, and answering that what if by saying that the success or failure of a tool ultimately doesn't matter, because tools aren't ways of doing things, in much the same way considering operating system to be better than another is mushing too much unrelated context together. It's very good to build good designs that excel because they are well thought out, but I've learned (without becoming cynical :D) that success and failure are ultimately memetic and arbitrary, and that bad things can succeed because they're in the right place at the right time, not because the fundamentals of the universe are broken or biased towards bad things succeeding, but because the technical discourse of "A is better than B" confuses the semantic priority of problems vs solutions, and thus typically do not consider (or provide room to consider) the almost-always-limited scope of the situations A and B might be being used in (the problems), which may not give any consideration to the majority of the ways A might be better than B (the solutions). The fitness function isn't about All The Things™ the solution brings to the table, it's about whether the solution fits the problem at hand. As for "but what about the future?", I think that ultimately boils down to understanding the problem space well enough such that all the things a current problem might need to tackle in the future become apparent in the present, so the solution can integrate those considerations from the get-go. To reiterate, it's about understanding the problem space correctly, not the solution space.
The above was written with more than a healthy dose of assumption, and I apologize if I've extrapolated nonexistent signal from your question.