You can't retain on the official pick like on Montréal's pick of Drouin

Islanders aren’t giving a first to get Eberle back. I don’t think that’s even allowed.

Not disputing this, however, I did hear someone on Sportsnet (I think it was Friedman, but don't quote me on it being him for sure) bring up the possibility of Seattle taking on Drouin if Montreal were to retain salary, so I think there must be some kind of loophole through trade that would make it possible.

I think it is allowed if I'm not mistaken; it's only considered cap circumvention if salary is retained when trading the player back to the same team if I'm not mistaken (ex. if Seattle were to select Carey Price and then immediately trade him to Montreal with 50% retained salary for a 1st round pick). Ottawa tried to reacquire Marc Methot after the Vegas expansion draft and I don't remember there being any rules preventing it.

You might be right there, but I still think it’s very unrealistic. If Lou exposed him, he’s prepared to lose him.