1. "No one will ever work anymore!"
Really? People do not care about material well-being, leisure goods or the feeling of usefulness? What does it say about our current labor market if, given a poverty line subsistence (!), the majority will choose to forego any superior value good? Maybe that we are forced to work, against our will? Where's freedom in that? If this is the case, we clearly have an economic efficiency problem here and now.
2. "Inflation will eat any gain, prices will skyrocket!"
First, if we consider inflation as "too much money printing", then paying for the subsistence allocation with a variety of cuts and taxes will not trigger inflation. Simple. As for price increases, well we already have something to counter these and it's called the market. As in the price increase signals to actual & would-be producers that there's money to be made by producing more potatoes, lodging, clothes, etc. This is textbook economics.
When there is talk of subsistence allocation (or UBI) too often common sense seems to be left at the door. Something reaaaally irks many people. I cannot help but think of it as irrational.
But I'm ready to be convinced otherwise!
edit: added invitation to discuss...