Agree with Chris. What's out there this year isn't that great. So whether the Cs renounce players depends on whether they'll actually use cap space. If they're not gonna use cap space, there's really no utility to renouncing free agent rights. They haven't used cap space for years, which is why they still have small cap holds for guys like Olowokandi, Dana Barros, Mark Bryant, Roshown McLeod, and a big hold ($8.3 mil) for Krstic.
I think that before deciding whether to pursue a trade for a guy like Jefferson or Josh Smith, or to make an offer to a restricted free agent like Hibbert or Gordon, Danny tries to resolve his own free agents first. Almost all of them have cap holds that far exceed what they'll actually get - KG $22.3 mil, Allen $15 mil, Green $11.1 mil, Bass $8.1 mil (if he doesn't take his $4.25 mil player option), Dooling $2.9 mil. So he'll want to figure out whether he can resign those guys, or sign and trade them, before renouncing them outright.
I don't know if he'll actually bring these guys back, but I do not expect him to renounce their rights without having figured out their market and sign-and-trade values.
But if they brought them back by using cap space after renouncing them, they would be giving up the rights to use the MLE.
As a team that paid the luxury tax this year, Boston would only have a $3 million MLE instead of the $5 million MLE that non-tax-paying but over-the-cap teams get, even if they don't project to be over the luxury line this year. But the new CBA also created a third MLE that can be used by teams that are under the cap during the offseason and use up all their available cap space on outside free agents. Once the space is used up, they still have a $2.5 mil MLE they can use for 1-2 more players. So the MLE isn't much of an incentive not to renounce, there's only a half million dollar difference between the MLE they get if they resign their own guys and go over the cap line as opposed to using their cap space to sign their own and other teams' players.
The incentive not to renounce is that if they have $25 mil in cap space, and they decide their best option is to supplement their roster of Pierce, Rondo, Bradley, Johnson, Moore and three rookies by bringing back KG, Ray, Green, Bass and Stiemsma, they're limited by that $25 million number if they've renounced their rights to those free agents. Then they could use $2.5 mil more on say Pietrus or another big. If they haven't renounced their rights, they can spend more than $25 million and keep all those guys, then use $3 mil on whatever they want to add. Their only constraint becomes the luxury line (you know they don't want to be paying the luxury tax for a team that's fighting to make the playoffs).