I wouldn't call Utah a near disaster, the off-target landing at Utah was really the key to how well it went, and the good leadership was realizing, once the first troops had come ashore a mile off-target, that everything would be much easier if everybody came ashore there instead of at the originally planned location.
Well, there had been two things happening that prevented diaster on Utah:
- They landed on a less well defended place of the beach without knowing it.
- And they noticed that they had been in a better position before the Germans did.
Omaha, on the other hand, I'm not sure qualifies as a merely a *near* disaster. If the other beaches had gone that badly, I don't think the operation as a whole could have succeeded.
Well, on the other hand, even with Rommel understanding the situation before invasion perfectly and preparing accordingly, the German leadership really made it easy for the Allies.
More so, without Rommel changing the defense plans in the months before to something more sane, D-Day would have been a beach picknick for the allies. The initial German plan was as insane as letting hundred thousands of allies land first in Calais, relying completely on the static and underequipped Atlantic Wall, and THEN engage them in a massive battle far away from the coast.
Thats like trying to win a football final against Germany by beginning with the penalty shootout.
if the bombing of Omaha would have been hitting the correct targets, that beach would have been much easier to take, since the Atlantic Wall was very vulnerable to bombing and ship artillery - as the other beaches showed this too well. As Patton said wisely: fixed fortifications are monuments to the stupidity of man.
D-Day could have ended differently. With a different German leadership and leadership culture... Especially Saint Lo and The Falaise Pocket later showed how the German Nazi system prevented an effective defense against allies. It was a tough hard fight already with so many idiots giving the orders. But IMHO, a better defense strategy would have resulted in the allies needing multiple D-Days to create the western front.
(Though as you said correctly: Winning a prolonged war was impossible for Germany once the USA entered the war logistically. An even winning a short intense war against England instead of turning against the USSR would have been unlikely under the known circumstances. Hitler luckily was an idiot.)