I don't think EA is that silly. Say LA still had Shaq, I'm sure they wouldn't put one guy as a superstar on defense and the other on offense since it's not like that.
I think Bowen will have the "superstar defensive freestyle" on the Spurs. Notice him in one of the screens. (Not that is says much, but using general NBA knowledge we know Bowen is the Spurs' perimeter defender.)
I'm pretty sure Manu will have some form of the superstar thing, as will Duncan. Like I said, till now what I've understood of the whole new feature is that you will be assigned superstar qualites based on your ratings. So I wouldn't be all too worried about one person max.
That's silly, I'll give a (way out there) example.
Shaquille O'Neal is a superstar on the Heat.
Amare Stoudemire is a superstar on the Suns.
Ron Artest is a superstar (defense wise) on the Pacers.
Kobe Bryant is a superstar on the Lakers.
Jason Kidd is a superstar on the Nets.
Now if you were to trade away in your dynasty for these players, I'm sure they wouldn't just assign one guy with the superstar capabilities. Each of them will do their own thing I thinks. Shaq will dunk big time, Amare will too probably, Artest will have the defensive superstar abilities assigned to himself, Bryant will have the swingman one, thus dunks with a bit more flare I thinks & Kidd will be able to do the nifty passes.
(Btw, don't assemble that team, it'll probably be fun for awhile then just bore you.)