I think FDR would continue as the depression is still going and I think FDR would like to lead America out of the depression.
This time he will not have the war spending to lead America out of the great depression. This could mean less stress and better health for FDR.
To bring about the major changes FDR wanted I think it takes more than 2 terms.
His health was already beginning to decline by 1940.
Without the trial of war, I can picture him retiring, and living until around 1948-1949.