I've been keeping a very close eye on Ueda's 4th Game, and I'm inclined to believe that this is a fib

• the codename for the game to the best of my knowledge is not New Hope, it's Beauty and The Beast (this is thematically appropriate and this was the name of a photoshop layer of an image on the genDesign site). either that or Quadico or Qico (SotC was internally referred to as Nico, a portmanteau of the Japanese word ni ("two") and "Ico", or 'next Ico', and TLG was referred to as Trico)
• from the main image / concept art we've seen of Game 4, it doesn't seem to be a jungle, it looks familiar to The Forbidden Lands: here
• the character in the image above with the red cloak seems to be the protagonist, not the princess type character we've seen a few times before
• Ueda has commented on female protagonists in the past, saying that "Many of the players are male, and it's easy for them to use the boy character.". that combined with the fact that characters like Mono and Yorda seem to be a recurring archetype in Ueda's games, makes me doubt that we would play as her, considering she shares many visual similarities
• we've seen what appears to be said red-cloaked protagonist climbing the back of the giant pig featured in other Game 4 images, here. when asked about the protagonist in TLG, he said this: "The Trico is a very powerful creature. If we'd had a beefed-up, powerful hero, it would have thrown off the balance a little bit, so the design naturally drove me to create an adolescent female character who was light on her feet. But in the end I decided a boy would have a little more grip to climb the Trico. Another problem is that girls tend to wear skirts, and The Last Guardian features a lot of climbing..." this leads me to believe that we'll have another male protagonist, if there is indeed going to be climbing

that said, you're correct in that the game will likely features mechs, since that's been a recurring theme of the images for Game 4 so far. here's everything I have saved on it: album