Hi Everyone – thank you for your patience. As was commented by someone below, Suphatra is no longer at Microsoft, but rest assured we are working on this feature.
This item is still on the backlog.
Hate to be the bearer of bad news. This item has been declined. There will be no work to hide or remove the reply button.
As many people have commented, a big ask is to help improve how people distinguish between giving a reply and starting a new message.
For that the focus will be on this item. “Better visual delineation between `Reply` and `Start a new conversation`”