Things certainly look a lot better for the Allies in the Far East.
A great many ground troops would have been freed. The East-African Campaign alone tied down five full divisions in 1941, plus all sorts of supporting units. Force levels in North Africa were even higher. Wiki says the 8th Army had seven divisions -and better ones with plenty of armor. Had just a tenth of these troops reinforced Malaya, the IJA would have been in for a hard time.
Let´s take a look at the air power:
In 1940 Gladiator biplanes played an important role in the air war in the Med. Since they would have been of no use in the UK, dumping them in the Far East looks like a logical solution to me. The same applies to the Blenheim Mk.I, there were hardly any left in the UK in 1940. In 1941 some rather modern a/c showed up on DAF´s OOB: Blenheim IV, Martin Maryland and Hurricanes. The latter were used up on Malta in considerable numbers. ~350 were delivered by carrier alone. DAF even had five squadrons of P-40C at the end of 1941. Once again, a little of that could have had a big impact in the Far East.
And last but not least the Navy:
The four modernized QE were as good as any BB the Japanese had prior to mid-42. Ark Royal and Barham might not be lost and as far as I can tell the RN lost at least six cruisers in the Med in 1940 and 41. The Med was also the No.1 hunting ground of RN submarines, who happened to have torpedoes that worked.
Bottom line: The British Empire would have to screw up a to harder to loose the Far East this time. If they don´t they would have vastly more troops to fight Germany from 1943 onwards.
The Balkans:
My gut feeling says if Italy stays out of the war, they´d not mess around there too. At least not by invading Greece. Yugoslavia would hardly face an invasion. With no Italian invasion of Greece and no Axis, there would be no UK presence in Greece, so there would be no reason for undue German pressure on Belgrade. Italy and especially Germany would still dominate the region.