It's likely just a typical mid cycle refresh, the usual stuff like minor cosmetic tweaks, updated infotainment, safety systems/driver aids, maybe some special edition/high end models. Hell, they might even fix some of the faults and design flaws!
There's a chance that they'll add a V6, but I think it's unlikely. I don't think Nissan are as delusional as to think that they're competing with Merc and VW pickups, which are clearly aiming at the higher end of the market (VW more now than previously with the updated Amarok). Nissan doesn't have the brand or the product to pitch the NP300 up there. Their competition is the likes of L200, Ranger, Hilux, D Max etc - all of whom have been downsizing their engines in recent times.
I'd also expect price increases rather than decreases (although that might be offset by extra equipment), last year Nissan increased their prices on 1st June and the NP300 price has gradually increased throughout it's life so far.
