While I'd certainly give Protas up for an extended Marner, I don't know that Toronto will value him enough to really make a deal work. Wilson is likely more valuable to them, at least based on my impression of their teambuilding strategy.
I feel like Washington can't have it both ways. They can't get impact players while also retooling with youth while also not dealing so-called untouchable players. Something has to give. From the press conference it sounds like they are going to put draft picks into play which I think is 100% the wrong move for a team that probably needs to restock the cupboard.
If hypothetically we're talking about Marner, trading a young player + picks for him is fine because he himself is young and would instantly become part of the new core for the next ~10 years.
Right now you can look ahead and pencil in a tentative top-9 of:
Leonard-Lapierre-Miroshnichenko
Protas-Strome-Wilson
Milano-McMichael-XXX (Cristall maybe?)
Malenstyn-XX-XX
Protas + picks + Kuemper for Marner puts you at:
Leonard-Lapierre-Marner
XX (Cristall?)-Strome-Miroshnichenko
Milano-McMichael-Wilson
Malenstyn-XX-XX
On the back-end we have Fever, Sandin, Alexeyev, and perhaps Iorio with a need to find a couple RHD. We'll have FA and rising cap space to sign guys as well, particularly while our younger core is still cost-controlled.
I don't feel like it would be a big mistake to spend draft capital right now if we're getting a top-end, impact, younger player coming back the other way.