Is anyone able to clarify whether these things are collectively referred to or considered part of the Gov.uk PaaS offering (and therefore will all be decomissioned) or not? It wasn't clear to me from the article and I'm not otherwise familiar.
The GOV.UK PaaS is a hosting platform for other government departments to host their own software in the GOV.UK managed platform (like a Heroku kind of thing).
They're investing more in their SaaS services (Notify, Pay, Forms, Prototyping Kit, etc) and deprecating their PaaS offering in favour of Kubernetes, which looks like it may be offered as a managed service for government departments to use. It reads to me like more of a v2 of the PaaS but it'll now be kube based rather than whatever homegrown thing it is at the moment.
Edit: as tnwhitwell pointed out below, the PaaS being deprecated uses CloudFoundry and isn't homegrown.
Most services are not using PaaS, but are deployed onto AWS or Azure and integrate with other services (notably Notify) via APIs.
It is incredibly cheap for our use cases (as it turns out, unsustainably so for the team who provide it!). Our interpretation of this news is that we will need to migrate away to another platform.