It's always been the sales model that the license is tied to the unit. Same with my Arcam SR250. It's just that the license cost was included in the sale price of the unit with the Arcam, not de-coupled as it is now. If the unit fails, I can transfer the license to a similar unit, but not to a different model.
In my case I'm not looking to upgrade from the x4800, but if it fails within a few years and that leaves me having to source a 2nd hand x4800, then yes, that would be a pain. Hopefully, as I'm using the unit purely in pre-amp mode it'll be less prone to failure.