Last time I had a Roku you could block the static home screen ads with PiHole. So as long as they don’t start serving these from the same domain as something you need for the box to work right or start hard coding a different DNS server into the OS that won’t respect your local network settings it will probably keep working.

But if they are not doing one of the above to get around DNS adblockers yet, they will eventually in the name of those sweet sweet ad dollars. Best to just start planning an exit from Roku products if you care about such things.