Peleliu bypassed: The 1st Marine Division in the Philippines

Just as the title states, Halsey's doubts regarding the validity of the Peleliu invasion based on the weakening air power of Japan is acknowledged by Nimitz, who promptly scraps Operation Stalemate and bypasses the Peleliu garrison. He then sends the 1st Marine Division as part of the Sixth Army in the invasion of the Philippines

How well/ badly do the Old Breed fare in the Philippines?

Will the bypassed garrison in Peleliu make good use of their situation or are they doomed to a slow death?

How will the abandonment of Peleliu as a whole affect the war in the Pacific?
Peleliu's garrison (14th Division) was completely isolated and truly was inconsequential to the war. All that really needed to happen was the Navy to bomb the airfield so they couldn't use it for scouting and then it die on the vine. It was too far away from the Philippines and New Guinea to support them and maybe the Japanese mainland would have been able to bring in some submarines to take troops off and get them to reinforce the Philippines.

The other issue you brought up was to divert the US units over to the Philippine campaign, my guess is absolutely no. Nimitz and Dugout Doug were not going to play nice.
The 1st Marine Division did not arrive at it’s rest camp on Pavuvu until May 1944. That is too late for them to fight in The Marianas in the summer of 1944. With no Peleliu invasion in September I think the Division would be used for Iwo Jima in February 1945. Maybe the 1st, 2nd and 3rd Marine Divisions assault Iwo Jima while the 3rd, 4th and 6th MarDiv land on Okinawa.