While Thompson rarely uses a significant portion of the available cap space on free agents he tends to overpay to re-sign the Packers own ones. The team has to address the #1 cornerback and outside linebacker position next offseason. That will eat up a huge part of the cap space.
I wouldn't be surprised to see the Packers stick with the current guys (minus Shields unless he restructures his contract to a much lower number) for corner next year. Also, the Packers have shown the ability to draft and develop corners while OLB, outside of Matthews (who was drafted by a much different front office), has been a series of disappointments in the draft. The OLB spot is a serious weakness with no potential solutions on the roster (Perry has flashed this year but he's only done so with Matthews on the field so i'm not convinced he's truly that great and I'm leery of relying on a guy who is frequently injured). Jamie Collins would be an interesting name, great player that fits a need and won't cost as much as his talent would normally dictate, but I doubt Thompson would take the risk on him. The best guys available in free agency, Melvin Ingram and Chandler Jones are going to be far too expensive but Collins would be a great guy with tremendous upside if you trust your coaching staff to get through to him; like when the Broncos signed Talib or the Giants signed Janoris Jenkins. Best part about Collins is that while he's elite at nothing, he's above average at everything and would really help the linebacking group with his coverage ability. Outside of that there really aren't a lot of options in free agency at OLB.
If the Packers do go to free agency for a corner then Jamar Taylor, Darius Butler or Logan Ryan might be decently priced options. Morris Claiborne has been very good in Dallas this year but he'll probably be fairly pricey, as will Bouye out of Houston (though Bouye would be ideal with his size and skill).
Honestly though, I don't expect the Packers to sign anyone who actually has the potential to make an impact on the defense this off-season; the team will just do what they always do and hope guys develop and re-sign Perry to a deal he probably won't live up to and sign Datone Jones to a one-year deal like Perry played under this year.