Agree with all of this. My only suggestion would be to open with Livingstone as he used to open for Lancs in 50 and it allows us to play an extra bowler.
Hard to see Bairstow, Root, Woakes or Malan playing another ODI and we already know Stokes and Roy won't. Rashid may hang on another couple of years but you wouldn't bet on it would you.
T20 side will stay largely unchanged for the next WC though.
Wouldn't mind Livingstone opening but only if there are more all rounders who could fill his place at 6 ir 7. It's not like England have a lack of openers and a ton of middle order batsmen coming through. Duckett, Crawley, Salt and Jacks are all openers, so moving them down the order to push Livingstone up the order doesn't really change anything. It's more about who is batting at 6, 7 and 8.
I think in ODIs it's imperative to have 2 or 3 of your 6 bowling options being strong batsmen, and ideally one or two more who can hit a few. Its allows the specialist batsmen to be more aggressive. England were blessed for years with Stokes and Moeen who were genuine batsmen (Moeen was inconsistent but certainly explosive), plus Woakes, Willey, Rashid, Jordan, Plunkett as bowling all rounders. Livingstone fits the bill, although his bowling isn't as good Moeen's. Curran has potential but so far, beyond a few T20 knocks and big scores in the County Championship, he hasn't really produced in ODIs and doesn't look like a reliable 6/7 just yet. Carse and possibly Atkinson or Jamie Overton are good options at 8-9 but don't think it'd be ideal having them at 6 or 7. Ahmed has scored some runs in County but I'm not sure what his batting is like in white ball, but given his skill with the ball I'm sure the team will be built around him regardless, but if he could be a solid middle order batsmen as well it'd be an incredible bonus.
Basically, England are crying out for the next Botham/Flintoff/Stokes. Every great England side has had a world class all rounder, plus a lower order who can chip in. Livingstone, Jacks, Curran, Carse, Ahmed and maybe Jamie Overton could between them just about be enough but a fully fit Stokes regen would be transformative. Someone who can bowl 10 overs and can finish an innings with the bat, stay in for 20-30 overs if needed, get themselves in and accelerate towards the end is more important in 50 over format, whereas having 3 or 4 players who can chip in with a quick fire 15-20 runs is more beneficial in T20.
The other worry is how little 50 over cricket these players I've mentioned actually play. They are either playing red ball, playing T20 or playing The Hundred. 50 over cricket is at risk of becoming a forgotten and unpractised format.