Why not trade for Lawson and Kanter. Try to extend Kanter for 10-11 mil per. Go after Tobias Harris in the offseason.
We basically would be moving Rondo/Bass/Green in the lineup for those three. We got bigger, younger (Rondo and Lawson basically the same age), and cheaper (at least in the case of Harris and Lawson who should be able to be had for less than Rondo and Green would have commanded)
If we can get by with paying Lawson/Kanter/Harris $33-35 mil, thats a pretty good deal. We can still build through the draft with the Nets picks.
Correct me if this is wrong, but we can replace a few players in '16 and '17 through the draft and keep our main group together:
2016 expirings: Turner, Sullinger, Zeller
2017 expirings: Crowder (if given a 2 year deal now), Olynyk, Lawson
2018 expirings: Bradley, Smart, Young
2019expirings: Kanter, Harris, '15 draft picks