Purely theoretical ofcourse.
They turn off all Homey servers on their side including the webapp and everything else.
Can I still manage my homey through either webpage or android app? And if so, indefinitely or will I run into issues eventually?
So basically, is it actually fully local or is it what companies like to sell as “fully local”
Homey is not, and never was a “local only” device.
However, for non-cloud devices, it can run unattended as black box w/o internet, until something breaks.
Athom descibes this like:
Local control is only possible for Android/ios app, but:
It depends on the bi-weekly authentication check process, which runs in the cloud.
Unfortunately there’s no possibility to set up local accounts atm.
Only here, Athom “admits” the catch in a very vague way:
Ok, thanks for clarifying that this is still the case.
I do still like my current Homey setup but I do find it kinda annoying that a company like this doesnt seem to give any value to actual independant local usage.
For cloud usage its obvious, but I already bought the Homey Pro and outside of downloading apps (or backup if paid for) there is no reason why it should communicate with Athom servers in any way.
Only obvious reason could be that they are scared that someone manages to put their OS on a different hardware costing them money (seeing as software is the thing they have going for them… not gonna comment on the quality or pricing of their hardware…), but can that really not be solved by allowing 1 cloud user that is bound to an Homey Pro to create 1 local user per device which has an identifier sent to Athom and is bound to that account meaning that as long as Athom servers are online, they can detect if an local user is used on a different device thus blocking that account and when athom servers have shut down/are not reachable that local account will still be usable.. or surely someone else can figure out something more elegant.
Anyway, going to far in my rant and you did answer my specific question already so yeah… 
Will hope Athom thinks about these kind of scenario’s (seeing this with more and more companies tbh, just this morning Belkin already announced shutting down their IoT servers which will basically break all their sold IoT devices) , but not holding my breathe then.
If anything, I think that Athom/Homey will move towards more cloud usage, not less, just like they did in the past. IMO, saying that Homey uses the cloud “only when necessary”, and then proceed to run the entire web interface (including features like Insights) and an important part of the app (authentication) in the cloud is pretty reprehensible.
Hmm, I imagine they will miss most of their target audience if they go even more into the cloud.
People who want to homelab it prefer the least amount of cloud, while people who prefer to have everything in the cloud will just use whatever brand-specific hubs they have an use seperate apps, they arent going to buy an Homey for that.
For now it works for me and I prefer it over home assistant, but if it turns out that in the future nothing changes or it goes even more towards cloud usage I can always just prepare a swap to home assistant.
Their target audience typically believes much of the marketing speak that surrounds Homey, only to find out after having bought the device that not all of it is true. But a lot of users will then simply accept that Homey does require cloud access to be able to function properly, or that certain functionality requires a working internet connection, or that certain protocols/systems are implemented suboptimally.
