Okay,
1. The Hurricane could still be used as a fighter bomber in the CBI as its main opponent was the K-43-II which had the same sort of performance clean.
2. The P-39 gave sterling service on the Eastern Front. It was the favourite mount of the Soviets top aces.
3. The P-40 was still scoring victories in the South West Pacific and CBI as it didn't have to combat the latest fighters of the IJN and JAAF.
4. The FM-2 had sufficient performance to act as a DLI against Japanese kamikaze and attack aircraft from the USN's jeep carriers.
None of these planes were obsolete, but their usefulness was reducing as the years went by. All were being replaced.
Agree with the above, with some caveats.
I think the Soviets still had use for the later model P-39s to the end of the war.
In addition to their effective use as fighters in the CBI by the Americans and Pacific by the Australians, the RAF was still using P-40s as fighter bombers in Italy to he end of the war.
They were still FM-2 or some version of the Martlet in the Royal Navy too I think. From the wiki:
"The last air-raid of the war in Europe was carried out by Fleet Air Arm aircraft in Operation Judgement, Kilbotn on May 5, 1945. Twenty eight Wildcat VI aircraft from Naval Air Squadrons 846, 853 and 882, flying from escort carriers, took part in an attack on a U-boat depot near Harstad, Norway. Two ships and a U-boat were sunk with the loss of one Wildcat and one Avenger torpedo-bomber. "
In a nutshell there were different types of Theaters, i.e. the Russian Front was much more focused on Low Altitude combat and had little requirement for long range, compared to NW Europe, and there were secondary (ala Italy) and Tertiary (CBI) Theaters where the 1941 and 1942 vintage aircraft still worked.
Not certain about the Hurricane in the CBI though I'd like to see some Operational history data for that.