Well, when we talk about one-shots, do we mean exactly like Kaido where it's just the first attack sent, or if an Admiral can KO Luffy with one attack landed?
Either way, all three of the original Admirals are gonna be able to do so(I'm excluding Fujitora because Luffy has a special resistance to his moves and we don't know what Green Bull does). If Kaido can blitz Luffy, I'm sure Kizaru and Akainu can. Aokiji also has ridiculous AoE, so I don't think Luffy can dodge a widespread freeze. Luffy effectively utilizing future sight has been on panel, what, one time? Aside from when he dodged Katakuri's Gatling-imitation, when have we seen future sight definitively enhance Luffy's abilities to the point that we can start attributing it to him as a regular thing in battle?
I took the discussion as could an Admiral do like Kaido and end the fight against Luffy in and with a single connected attack. Maybe I was being too literal? But in that sense I don't think Kizaru would be able to land a laser shot to the heart or brain in the first attack and I don't think he has an attack comparable to Kaidou's strength to KO Luffy with a single hit. I think he could blitz him and kick him but that kick wouldn't put him down and firing a laser from any distance I feel would give Luffy too much time to dodge, he was dodging Pacifista lasers which are pretty much comparable to Kizaru's, or at least nothing has said they are inferior in any way.
If Kaido can blitz Luffy, I'm sure Kizaru and Akainu can.
Granted one is light and the other is a top tier but why are you sure they can do the same things Kaido can? Kaido was said to be a unique case in 1v1's now I know that doesn't make him the fastest or strongest character but I wouldn't say just because he can do something against a particular guy and they are close him they could do it against that guy too, that's bordering abc logic.
when have we seen future sight definitively enhance Luffy's abilities to the point that we can start attributing it to him as a regular thing in battle?
Not a regular thing but he has increased it's abilities from fighting Enel to Mihawk to Kata and like Mihawk maybe it's only a life or death moment but that's the scenario we're talking about now, life or death. Luffy was also irrationally angry with Kaido and as we saw against Kata that can disrupt Ob haki, I think when cool headed he has it to a point now where he would be able to avoid lethal hits while healthy, which to be a real one shot would have to occur while he's still healthy.
Aokiji also has ridiculous AoE, so I don't think Luffy can dodge a widespread freeze
True, he may not be able to dodge it but we don't know that he would remain frozen either. We have the Doffy instance and for whatever reason he was able to break free, this could be because of his own strength, Aokiji not putting full effort or even possibly Doffy using conq. to get out though that one seems least likely. We then also have Luffy showing to be able to break free of Parasite which iirc no one else was able to do. Also about Parasite, nowhere was it said Doffy's strings had varying levels of strength so the Bridcage strings were as strong as Parasite strings for what it's worth and no one was able to cut them. So Aokiji probably could hit Luffy with Ice Age and freeze him quick, but, I feel you can make a case there's a chance Luffy could escape that since he was able to snap strings that Zoro and Fujitora were both unable to cut.