I hope they kinda don't. The refinements made in Far Cry 5 were wonderful. They don't need to completely reinvent the wheel.
Exactly, what I would like is more mobility in the world, they already did planes in 5 though so not sure what else... mole machines! No but seriously, maybe they could do something interesting with the narrative where if its set in a city then story progress is often contained inside buildings so it can be more linear, but you still find it when you want to since it'd be obvious its a special area from the outside, but also sometimes its totally innocuous and you stumble on an elevator to a super secret place in a tiny outbuilding.
I didn't mind the bits where I got abducted because at least it meant I didnt have to go and do the story missions to advance the plot to gain more playable area in 5 like I did in 4, and especially 3 & 2. So it would be nice to see some other way of integrating them into the open world than what was done in 5.
Ultimately I don't really care about the narrative, as long as it has some silly what-a-mentally-challenged-hipster-thinks-is-cool dialogue and over the top situations I'll enjoy it, 5 was pretty funny for all that stuff.
What I really want is more exciting treasure/mini-locations and more of those HL style bunker/treasure puzzles, I really enjoyed that in 5 a lot and I wanted more exciting ones among the rest of the trad ones. What I used to enjoy most from Far Cry 3 onwards was searching everywhere to find cool locations with a view or interesting interiors and treasure, finding and hunting the animals to get upgrades.
I realise the animal hunting can only go so far before you run out of ideas and thats prob why they dropped it in 5 but I hope they bring a twist on it for the 6th installment.