From Wiki:
Tarawa
Of the 3,636 Japanese in the garrison, only one officer and sixteen enlisted men surrendered. Of the 1,200 Korean laborers brought to Tarawa to construct the defenses, only 129 survived.
Saipan
In the end, almost the entire garrison of troops on the island — at least 29,000 — died
Iwo Jima
US
26,040 total casualties
6,821 killed
2 captured but recovered[4]
19,217 wounded[1]
1 escort carriersunk
1 fleet carrierseverely damaged
1 escort carrierlightly damaged
Japanese
17,845–18,375 dead and missing[1]
216 taken prisoner[1]
~3,000 in hiding[5]
Okinawa
US
20,195 dead[6][7][8]
12,520 killed in action[9]
38,000 wounded[10] to 55,162 wounded[6][7][11]
Materiel:
221 Tanks destroyed[12]
12 destroyers sunk
15 amphibious ships sunk
9 other ships sunk
386 ships damaged
763[13]–768[14] aircraft
Japanese Personnel:
From 77,166 killed[15] to 110,000 killed (US estimate)[16]
More than 7,000 captured[16]
Materiel:
1 battleship sunk
1 light cruiser sunk
5 destroyers sunk
9 other warships sunk
1,430 aircraft lost[17]
27 tanks destroyed
743–1,712 artillery pieces, anti-tank guns, and anti-aircraft guns[18]
40,000–150,000 civilians killed out of an est. 300,000[16]
I really don’t think that Japanese resistance in the Pacific could have stiffened much for any reason. They fought to the death. Ask a Pacific vet what he thought about fighting the “Japs” in WWII. My father’s friends hated them so much you couldn’t talk about it in polite conversations.
Let’s say there was no unconditional surrender.
Does the world find out about the death camps?
US and Russia don’t get a jump start on rockets or swept wings.
The nuclear genie is out of the bottle (Not used, but probably tested). As they say, once you know something is possible, the rest is just engineering.
You now have two of the most reviled regimes in history trying to get nukes. Now you’re probably back to the aftermath of WWI again. Nothing settled, countries hating each other, but now with nukes, ICBMs and even better bio and chemical weapons.
Completely agree with Jack Brisco. The world of today is a much better place because the Allied leaders of WWII demanded unconditional surrender from the Germans and Japanese.