I'd actually prefer Pratt to Brolin now that I've had time to think about it. I do like Brolin and I think he would have been a good fit too, but he's been in a lot of lead roles in resurrected franchises lately, or movies in general (MIB III, Gangster Squad, Old Boy, Sin City 2, etc.) He's already a pretty well established actor and I think he would have been a little too predictable go-to choice to cast as a lead in JW. Pratt, on the other hand, is a rising star right now and I could actually see him in a Jurassic Park universe. Irrfan Khan would be a great supporting actor as well. (in case you guys didn't know that he's being rumored as well)
Still hope we get some returning cast members though. It's the JP tradition! Maybe Goldblum can make way for it now since ID4 2 has been (unfortunately) pushed a year back.