Seems to me, what would make the most sense (if possible) is a trade where the Leafs retain $1.2 million of Liles salary for the next three years (instead of 6 years under a traditional buy-out). That would give them another $2.6 million to add to the Kadri/Fraser resigning efforts for about $7.4 million in total. That should be enough to get them both signed, particularly if either Kadri or Fraser were willing to take say a 3-year deal, where the money goes up a bit next year and the year after.
Liles at $2.6 million is not a bad deal for a team in need of some help on the PP, at a term of only 3 years. If the Leafs got a mid-round pick or a prospect in return that would be a bonus.
Moving Franson over Liles makes no sense. Franson, younger, bigger with more upside, not to mention a right-handed shot. The Leafs are loaded on the left side (Gunner, Gardiner, Fraser, Rielly coming)