Looking at the times on power of 10 (
https://www.thepowerof10.info/rankings/rankinglist.aspx?event=400&agegroup=ALL&sex=M&year=2021) we've not a single man under 45 seconds so that definitely won't help. Not a single individual athlete even made the 400m olympics for the men and the men's 4 x 400m were pathetic in the heats.
I do wonder whether it's time to get something in place, where we can get our top athletes under 1 roof pushing each other, as opposed to separate coaches etc... Not sure how it would all work logistically though.