DL, yes, it is Concourse J I believe. 28 gates. All will be used exclusively by United and Star Alliance partners, while the new 58 gate American Airlines/Iberia hub is for AA, Americna Eagle, IB, and OneWorld partners (although there probably won't be enough room for all OneWorld flights to depart from the AA terminal).
Klm UA pulled out of LIM and PTY because they grew too fast. You can't just say "Okay, we're starting a Latin hub in Miami, let's go". They expanded too fast for thier own good. They were not established in the Latin market like American Airlines, Iberia Airlines of Spain, and LanChile (which also serves routes to Ecuador and Peru from Miami, and they used to codeshare with QA on MIA-SCL-SYD, but I think that QA now does it only with AA on MIA-LAX-SYD). As time goes on, they can become an established airline to Latin America from MIA. Things take time, and any airline fan should know that.