To clarify, I am envisioning the ultimate compromise on PoWs being made in a matter of two months, instead of two years. [It involved acceptance of the voluntary repatriation concept, with the proviso that non-returnees would be interviewed by a panel of home country, neutral and allied personnel before the determination would be made]. Why does Mao lead us to this outcome earlier? Because, having decided for other reasons to end the war, he rationalizes that letting a few traitors escape...for now...is OK. Chinese population growth would replace them in a couple weeks.
...moving on from that...
Follow-on considerations:
1. After the OTL armistice at the beginning of the Eisenhower administration, Truman is alleged to have said he would have gotten politically raked over the coals for accepting the same (stalemated) terms.
On the other hand, its not like the continuation of the stalemated war on its current trajectory was politically beneficial for him either.
Net political impact within US?
2. Stalin is cited as having pushed keeeping the war going, even while the North Koreans were hoping to end it. If Mao's decision to end the fighting is disappointing to Stalin, will there be any payback in Sino-Soviet relations?
3.If China is not engaged in active fighting in Korea after the middle of 1951, can it reallocate major support [short of combat troops] to the Viet Minh? Could this accelerate their success, and generate a Dien Bien Phu or an analogous French defeat and decision to quit the fighting in 1952? [I found it notable that Dien Bien Phu in OTL came within a year of the Korean armistice and was aided by significant Chinese support].
4. Acceleration of 5 year planning, industrial programs, anti-landlord campaign and collectivization in mainland China?
5. The fighting as it was from say June 1950 to May 1951 had already set several developments in motion helpful to Japanese and West European economic recovery and rearmament. But without partial war mobilization for another two years [as in OTL],would this be significantly reduced, resulting in less economic success for US allies and a less prosperous 1950s in the west overall?
Would West Germany be inducted into NATO later, earlier or on OTL's schedule (1955)
6. Are there any other foreign policy crises that Truman would have been more hands-on with, in the absence of a regional war for the last year and a half of his term?
7. Would Stalin still send his note on German reunification in 1952?
8. What would be the consequences for North and South Korea? I think South Korea would benefit, but for North Korea it would be hugely positive.