This is a pretty unlikely scenario, but after seeing some of the expected contracts for Pietrangelo it at least entered my mind. It seems the pundits have settled on STL is offering $8 x 8, and on the market they're thinking he'll make about $9.5 x 7. That's below market IMO. I don't think any other team could compete with a top four including Heiskanen-Pietrangelo and Lindell-Klingberg. Long-term, you absolutely could lose Klingberg or Lindell (trade to make cap space for Klingberg). You can make it work though for at least 2 years easily.
Expansion actually works as well. To sign Pietrangelo, you have to move Radulov who is only due $1 million next season, and he has a limited trade clause. That opens up and expansion slot as well.
You protect 4 D and 4 forwards. Benn and Seguin have to be protected. You take a risk and give Faksa a 1 year deal this season making him an UFA this summer during expansion. Seattle shouldn't make poor decisions and draft UFAs, and if they do, there's no guarantee they sign. You then only have to protect 2 of Hintz, Gurianov, and Dickinson.
LeBrun speculated that Vegas, Toronto, and Calgary are the logical landing spots. Dallas and Vegas offer significant tax savings. I think you could make a solid case for either team that they're the better landing spot. The downside is Dallas could really use offense, but maybe you don't pass up creating a really solid Top 4.