I foresee the cycle of innovation will be: 1) offline (PAST) 2) cloud-hosted (PRESENT) 3) cloud hosted but with full offline support (FUTURE) This way we'll have the best of both worlds.
What's good about cloud hosted POS you ask? Well they do update easily. So you are not stuck with the same system with 90s UIs.
Also by upgrading faster and being connected to the internet the POS is able to interface with external systems. Currently 99% of restaurants use a separate tablet for each online delivery service (deliveroo justeat foodpanda...).
This doesn't require "cloud" at all, just network connectivity. Software auto-updaters are no more complicated than zero-downtime cloud deployments. Especially in fully controlled environments where issues of users randomly switching off autoupdates or blocking Internet connectivity are probably nearly non-existent.
I'd argue that the software is more resilient if it runs locally. One can argue that cloud can be updated "in realtime" but live code updates had existed since forever (at least since eighties, with Erlang/OTP), and running locally makes things robust against network outages (or degradation) - which is probably way more frequent issue than getting the latest updates immediately.
This is one of the reasons why that entire "cloud" SaaS thing is a bad fit for PoS systems to start with. It doesn't stop cloud apologetes to still develop and market such systems and customers who drank the cloud kool-aid to buy them, but what people actually want in that business when push comes to shove is a locally-installed system that is seamlessly offline-capable in all its core features, can send transactions out and receive new master data in real-time while network connectivity is available and can be updated easily and ideally via a centrally controllable and plannable process. And that have actually been bog-standard features for PoS systems for at least a decade or two, long before all that "push everything into the cloud" hype started.
It does provide resilience but it also increases the complexity which may not be the right trade off in some instances.
How are constant UI changes a good thing?