If I'm hearing you right, the concern here is not lack of support for BC itself on-premise, but for Flow and other such integrated tools?
I know there are already a few things the cloud version offers that on-prem will not. There's no doubt in my mind that MS will try to herd us all into the cloud asap. It's a lot to ask of a company to put their entire ERP into the cloud when security is an ever-growing risk. Some simply do not have that option at all due to the nature of their business. It's also going to be difficult for partners to sell on-prem if consumers do not have faith that it will be around more than a couple years.
If you've found this thread useful, dive deeper into User Group community content by role