DISCLAIMER: I just got off a 14-hour flight, about to step onto the next plane in a few minutes, and an jet lagged AF (ie: I’m not at my sharpest at the moment). Quick thoughts that will possibly get expended later:
One of the reasons it might fail is because it’s a large, monolithic change
I’m inclined to agree. A few times I’ve started breaking this proposal up into several sub proposals linked by the requires metadata field. As @gcolvin mentioned, EIP-615 has been in process since 2016(!), is referenced in Gavin Wood’s book, people know the number, it’s been discussed with lots of people that like it, &c &c &c. I do agree that some parts may be more controversial (the push/pop optimizations), and more granularity makes it easier to show progress on the portions that are absolute no-brainers.
Yes, they’re all part of a single strategy, but I’d call adding any number of them a win.
True, though compared to eWasm it’s tiny
Oh yeah: like a completely different scale of change! I think that the difference is that there is already political will to advance eWasm. Obviously I believe that there should be effort into improving the EVM, and the base changes (literally just subroutines and static jumps) are essentially uncontroversial.
Be careful; that assumption is what bought us the issues with net gas metering.
Yes, everything that goes into the spec should be solid. My views on having a formally-verified canonical spec are well known at this point 
Now if there was funding for these initiatives, that would be amazing!