Pruning has been available for nodes for quite some time now. You may need to download the whole chain once, but you only need to store as little as 6GB, including daemon executables.
Yep, and if your disk gets corrupted or damaged or whatever, you still need to download the whole thing again to get back to as little as 6 GB (it's less than that actually, but whatever). You're backing the irresponsible idea that the 125 GB needed, even for a pruned node, should start growing at 8 or 16 times the current rate. We could have a 1 terabyte blockchain by the end of the year, and that would seriously hurt the number of people willing to download such a huge database, despite the benefits it brings. But the miners can just run Bitcoin all on their own, right?

Besides, Segwit only increases the storage requirements for nodes. The total of the witness and block data becomes larger.
Yep, and I'm on record saying I'd prefer less than 4MB blocks with Segwit, but hey, here we are, accepting the compromise between Big Blocks and actual scaling paradigms. Oh no, wait, you just keep saying over and over again that miners should be given the right to force whatever blocksize they like on people, huh? My bad
And, has anyone solved the "Anyone can spend" issue of Segwit transactions?
Litecoin is stagnating and waiting to dump after Segwit adopts on it.
Has anyone solved the "anyone can spend" issue for the 10 or so other soft forks that are already activated on the Bitcoin network since months and months ago?
"anyone can spend" _is_ the soft forking mechanism, trying to twist things so that it's some kind of problem only demonstrates how desperate you all are, you know full well that nodes will reject someone trying to spend BTC that's not theirs, as ANYONE_CAN_SPEND is just the backwards compatibility logic that allows pre-Segwit nodes to "understand" Segwit transactions without actually needing to understand them at all.
Your FUD is pure comedy, big
dicks blocks propagandist in chief Gavin Andersen couldn't even try that one with a straight face