McKenzie says Philly is most likely looking for a 2nd line C to shelter Patrick and let him develop.
I think theres a fit there for Kadri. They have pretty good currency in young dmen
They could possibly offer Sanheim, who plays RD, but I don't see them doing a deal involving Sanheim unless Zaitsev is added in there as well to replace him (since Philly would only have Gudas, MacDonald and Myers as NHL ready RD). Sanheim is a pending RFA, and he's probably going to want something in the 5 mill range over 7 years, since that is close to what Theodore got. That's probably reasonable.
What about something like Kadri and Zaitsev for Sanheim and Rubtsov? If Philly is high on Rubtsov, there are alternative B-level prospects they could offer, but he was injured for most of this year and has not exactly progressed like a typical 1st rounder. At best I think he becomes a solid 2C or high end 3C (which is perfect for the Leafs) and he's not going to be NHL ready for at least another couple of years, so I think he's fair value. We can even throw in Joshua for a 6th this year (to replace the one we lost) so they have a guy who can immediately replace Rubtsov in the AHL next year, but that is not really necessary.
Sanheim becomes Rielly's partner, while Dermott can replace Zaitsev as Muzzin's partner. Dermott will need to learn how to play RD, but he's already doing it now (with Gardiner no less) and he'll have an entire summer to further his skill over there. He has played a bit of RD before as well, so he's not entirely new to it.