From what I've read it was an extremely regional thing: in places where the landlords lived in their communities and oppressed them personally they faced justice at the hands of their former victims (which ranged from execution to being subject to public tirades recounting the suffering and hardship they'd inflicted on others - they were only killed when their victims felt it was necessary); in places where they instead lived in cities and had someone else run their rural land holdings they usually either fucked off to another country or cut deals with the CCP similar to those that many former factory owners did, peacefully surrendering land and capital in exchange for party membership and jobs as bureaucrats (on account of the CCP desperately needing literate workers as soon as possible, and since pre-revolution literacy was systematically denied to most of the population that meant recruiting former bourgeoisie/aristocrats and what we now broadly call the professional managerial class while the large scale literacy programs were still being implemented and rolled out).

It has to be understood that it wasn't exactly that they were killed for their land, but instead for crimes they'd committed against the people who lived and worked on it. So when they weren't personally overseeing that violence themselves it was instead their agents that faced justice while they themselves could either flee or join the new system.