It's hard to believe something like that gets a net energy yield from burning the syngas, also technologies around syngas seem to struggle when competitive fuels are available.
The construction material bit is definite downcycling and even that sort of plasma torch might destroy PFAS it is (i) not going to destroy or isolate toxic metals like like and (ii) it is not going to extract various precious materials that are widely dispersed in waste: so low-value outputs can't really be good.
I've heard that the plasma torch can be tuned up to separate elements, at least coarsely, and if it could produce high value products it would be a big help.
My understanding is there really is no shortage of landfill space there is more of a political unwillingness to build more landfills. There is a huge interest in a "circular economy" but that precludes downcycling and of course making products recyclable is a start.
Another I find interesting is that very similar chemistry is being proposed for battery recycling as is used for reprocessing spent nuclear fuel, it seems a technology similar to PUREX could be tuned up to extract just about anything out of a mixture of everything in the periodic table but probably not economically. Similarly there are all the "pyroprocessing" techniques based on molten salts and such that are not so discriminatory as PUREX but more so than the plasma torch.
