Adrian Kempe
Of the players on this list, Adrian Kempe has the most uncertainty but might be the most important extension for the Los Angeles Kings this summer. He has been the team's best player for a number of seasons and is just entering the prime of his career with back-to-back 70+ point seasons.
The reason that there is the most uncertainty around these negotiations is that Kempe is going to warrant a big contract. The Kings need to make an offer that can convince Kempe to not wait for free agency and go to an open market that probably pays more.
For the Kings, the good news is that the salary cap is not going to be an issue with over $35 million in cap space starting next season. They won't have to worry about fitting a contract that probably is going to be over $10 million AAV.
It wouldn't be surprising to see the Kings at some point agree to an eight-year deal worth close to $90 million. That is a contract that can make sense for both sides and ensure the Kings' keep the most important piece to their future in Los Angeles.