so far, I'm not
I'm used to Far Cry being so exotic and distinct that this announcement is kind of disappointing. Montana doesn't sound exciting at all. especially if the setting is modern-day and not some other time in history.
To be honest, that's precisely why I'm interested. I enjoyed Far Cry 3, but I dropped Far Cry 4 only a couple hours in because it just felt so extremely similar to 3. Everything felt very "been there, done that" and made the game feel like a chore to play. If 5 had been another mid-20s-protagonist-in-a-foreign-war-torn-country setting, I would have completely ignored it altogether. I was already hoping for a Western theme for 5, but I think making it a modern Western is even better. Modern Westerns have been pretty popular in films recently, with examples like No Country for Old Men and Hell or High Water, but I can't really think of any games that have tried exploring that theme. I think it's pretty obvious that they're hoping to compete with RDR2 with this, and I think taking the modern approach was definitely the right way to differentiate themselves. They're still probably going to lose, but if they just tried straight up classic Western vs. classic Western head to head, they would get destroyed.
All that being said, though, it's still Ubisoft. I love the idea of a modern Western game, especially a modern Western open world FPS, but the fact that Ubisoft is behind it already has me bracing for disappointment.