Lakers don't have to trade their pick to get top talent. They can throw a max deal at Melo, James or Bosh in the off season, pick in the top-5 and surround that cast with a solid bench of ring chasers. Working on the assumption they get Bosh (the lesser of the 3) for $17M/yr ($70M/4yrs or $85M/5yrs), their pick falls outside of the top-3 and they decide to pick Smart and re-sign Pau for $10M/1yr with a team option for a 2nd.
Nash/Smart
Kobe
Marion/Rush/Ariza @VetMin
Bosh
Pau
Any competent ball handler will thrive with Kobe, Bosh and Pau (See: Mario Chalmers). Smart will have a very successful first season "backing up" Nash averaging 37mpg. Oh and if they can pawn Nash off on someone as an expiring in the off season they can probably sign Danny Granger for $16M/2yrs. This is life in Lakerland.
That is the rub with the current NBA. Large markets have a marked advantage in attracting FAs because of their opportunity for endorsements. Bosh can take a little less than max $, Pau can take a little less than his market value and the Lakers can add 2-3 very talented pieces around Kobe all by virtue of the LA market.
Oh yeah and if Smart doesn't pan out they can always take a swing Rondo if FA after the season.
All that said I'm not sure I trade Rondo for anything outside of a top-3 pick. I think Rondo might be one of those rare loyalty guys who you have to keep when you get them. KG was one, Tim Duncan is another. Guys who marry all-NBA talent with a sense of pride for the team they play for. From what I can tell Rondo is that guy. I think he is smart enough to understand the business and still stay loyal to his fan base. You keep those guys.