I'm not sure I 100% agree with the players you consider core as I would likely swap RNH and Eberle, but I do agree with what you stated.
Our biggest problem is the unwillingness to make meaningful moves. The Oilers have bought in to the hype that they themselves sling out. How much better could we be if we traded some of those draft picks rather than piling on young, similiar players.
Hall's (or Seguin, going back to the draft) we keep for sure. Maybe RNH. But the Yak pick? Why didnt we trade that? The Nurse pick? Why didnt we trade that (particularly early on when it could have been a better pick than it was)? The Drais pick? Why didnt we trade it? This years? I wonder what level of immediate help this years 1st + one of our "core" players could fetch us? Perhaps the thought of McDavid is too good to pass up but I personally would be shopping an idea similiar to this rather than rubbing my hands together planning on the hype I can build around McDavid.
We just hoard all of these players that all require development on sound teams surrounded by sound players. Instead we throw them all together and hope they can all lean on each other. Oh well; the past is the past I guess.
I hope they do recognize a core of 3 or 4 players and trade the rest, whoever they may be. Hoping that Hall, RNH, Eberle, Yak, Schultz, Drais, Nurse, + whatever else sticks to the wall (Klef, Hunt, Marc, whoever else) all miraculously have their stellar year at the same moment is infuriating.