I would think this means that Ainge will "rent" our cap space this season, not next, by taking on an expiring, using a TPE, from a team that is paying luxury tax.
Example:
C's
KG
2020 1st rd pick (unprotected)
Nets
Rondo TPE
The savings the Nets would receive would be huge. Plus, we get another 1st rd pick from them, albeit years down the line, for taking on a player that could be a positive influence on our young team for a few months.