The return in a trade for Brook Lopez, Thad Young, and Joe Johnson is not likely to be much.
Best route for the Nets is probably to simply gut through this year, see if they have anything in guys like Larkin, Hollis-Jefferson, Robinson, Bogdanovic, etc, and then use cap space next summer to try and cobble together a team that can compete for the playoffs in 2017 and 2018.
My main free agent targets, if I were them, would be Conley, Derozan, Nic Batum, Gerald Henderson, Eric Gordon, Luol Deng, Jeff Green, Brandon Jennings, and Marvin Williams.
Adding a few of those guys to what they already have in Young and Lopez would put them in position to compete for bottom playoff seeds for at least a couple years, which is the best they can really hope to accomplish in the near future.