Sure. It is okay to talk about whatever a person or company wants. It is also stupid. But, being stupid is is allowed.
Less literally: I think it is generally unadvisable to announce a game multiple years before release. The primary problem is that it starts the clock ticking in fans', heads, which then puts pressure on the devs individually, and the publisher, to get the game to market ASAP. There's enough pressure from the business side, needing to get the game out to generate revenue. They don't also need the social pressure of fan expectations bearing down on them for years and years.








