There's a lot of "it depends" in regards to a game that is fully completed at 25-30 hours. If Ubisoft is going to charge $70 USD for the game, along with an additional Deluxe Edition that costs an extra $30, I'm probably not going to buy it on release unless the story is phenomenal, and it's replayable.
I'd be the first to agree that the more recent releases (especially Valhalla) have been too expansive. The only thing that kept my interest with Odyssey and Origins were the settings (I love ancient Greece and Egypt). I think a 50-60 hour game is adequate for a AAA game like Assassin's Creed.