If he goes to NJ, they risk losing one of Holtby/Blackwood in the expansion draft or having to work out a deal with Seattle to protect both of them.
That's what makes this a difficult time for him to be heading to UFA. Best bet is a team that doesn't have a younger goalie they would also need to protect.
Nashville could certainly use him, though both Rinne and Saros are still under contract next season.
If Holtby can't find a long-term contract he likes (like Lehner struggled to do), I would certainly be in favor of NJ overpaying him on a 1-year deal (like they did with Simmonds this year), which would take him to UFA again after the expansion draft and open up his options. Highly doubt it comes to that though.
Would have to think any long-term deal Holtby signs would also come with a NMC to protect him against the expansion draft.
I could see Buffalo being a fit.