So it's just a theory, I didn't find more details about the 150th champion we will get than this and few spectulations tho, but just by reading that
again, if you just read and do not know what they are talking about, doesn't it just sounds like Yasuo? so that is one of main reason I believe it would be Yone.
Second one, Riot Game alerdy brought some people back from death and gived the the black power of being op (Senna), so I think it is possible for Yone to be bring in game.
There are like 2-3 variable I think:
1. They will change again the story, which I hope not, but we know Riot loves to changes everything about runeterra to force champions fit in, so they could change something there and there and boom, Yone is alive!
2. They give some plot armor like he faked his death or he seems like was killed but barely survived, when he awake tho Yasuo was alerdy gone .. etc you got it.
3. Someone ressurect him, I bet he will not be the first or last to literally come back from death, Morde literally did it, few other champions too.
As on gameplay we can be sure if Yone get ever released he will get at least a knockback ability or interaction with knockback to be able to have synergies with Yasuo, even if he will be most likely forced on top or mid lane, I remember Riot didn't really like champions to be viable to more than a single lane and a single role.