WI the CIA let Arbenz remain in power in Guatemala?
ETA: Please no Teh Ev0l Commies make Arbenz into teh Stalinz. This is a serious attempt at a look into how guatemala might be different.
There are some scholars who argue Arbenz still might have failed or been kicked out by the military anyway, both because of his own timidity and the intense hostility of elites towards any reform at all.
Arbenz's decree only took uncultivated land under very specific circumstances and it paid the owners a fair price. The Communist Party was relatively small and unions still weak. If he stays in power there's likely still quite a bit of unrest, probably private death squads carrying out killings. But that's still a huge improvement from the eventual mass slaughter and depopulation that hits Guatemala. IOTL Guatemala was the only Latin American country whose population steadily declined.
A lot would depend on how else the US would almost certainly still pressure him. I don't expect that this would reverse the pattern of coups throughout the region, but it might slow it slightly.
A minor effect would be the Bay of Pigs invasion is launched from elsewhere, probably Yucutan in Mexico.