Would we still have landlords in a post-scarcity future? Surely if all wealth is being generated by AIs, it's the end of capitalism.
Even if we introduced UBI today, this doesn't make much sense. It wouldn't mean everyone just gets more cash because tax would have to rise to compensate.
I think you're imagining that landlords would think, "oh everyone is getting an extra 100 zorkmids a month, so I can raise rents by 100 zorkmids". But it couldn't work like that because the cash has to come from somewhere; what would actually happen is that someone receiving 100 zorkmids in benefits now gets 100 zorkmids in UBI, and someone who was paying 100 zorkmids in tax now pays 200 zorkmids in tax and gets 100 zorkmids in UBI.