With digital it's most likely the series highest opening.
Most likely, but this certainly was the most expensive game in the series to date and, as far as I know, it was decently publicized over there, and yet it didn't seem to reach too many people outside of the core fanbase. They were probably betting on the West (like most JRPGs nowadays), and well, they caught my attention enough to buy two Premium editions, it had a good opening in the UK, so I'm confident the game will end up doing good.
My bet with The_Liquid_Laser: I think the Switch won't surpass the PS2 as the best selling system of all time. If it does, I'll play a game of a list that The_Liquid_Laser will provide, I will have to play it for 50 hours or complete it, whatever comes first.