I'd personally try trading Lebron, but that won't happen.
Which leaves the challenge doing all you can this year with a hope of extending the window with Lebron as long as possible. The Brooklyn pick is not enough of a sure thing to count as "help" for Lebron to win in comparison to trading for more immediately ready help.
A few ideas:
To LAC: Frye, Shumpert, JR Smith, BKN 18, (and other picks?)
To CLE: Deandre Jordan, Lou Williams
Why? Deandre fills a need and has 2 years left, possibly enticing James to resign for 1 year and run it back when they lose to GSW
To MEM: Frye, JR Smith, BKN 18, (and other picks?)
To CLE: Gasol
Why? Gasol is rumored to want out and Memphis ain't going anywhere. Gasol would be a bit duplicative of Love but versatile enough to be C to Love's stretch-4.
To LAL: Shumpert, JR Smith, BKN 18
To CLE: B Lopez
Why? Lopez is on the outs in LAL and they are hoping to continue rebuilding with picks (and probably planning to lose their own pick this year). I don't think Lopez is worth the BK18 and I don't think LAL would want Shumpert and Smith contracts, but they'd get the BKN pick which some dumb GMs are still high on.
And my personal favorite from a narrative sense
To MEM: JR Smith, Frye, Tony Parker, BKN 18
To SAS: Shumpert, Chandler Parsons, Tyreke Evans, CLE 18
To CLE: The Gasol Brothers
Why? No way Tony gets traded, but Memphis would get 2 expirings and the BKN18 (while needing to absorb Smith's contract, SAS gets an extra pick and a challenge to see if Pop can resurrect Parsons and make functional consistent use of Tyreke, and Cleveland gets the Gasol brothers. LOL.