McDavid (or Draisaitl for that matter) really shouldn't care about such empty platitudes as "respected", "productive", and/or "valued teammate" if at the end of the day Holland (or Pretend Holland in this scenario) is able to confidently tell them that the result of an RNH trade has made or will make the Oilers a better hockey club and a move that gets them one step closer to the Stanley Cup. That's the goal here, and that's what will convince McDavid to stay beyond the end of his contract- not whether he likes the guy in the stall next to him or not.
I've noticed throughout this thread you keep trying to attach emotional bias onto a pretty black or white question: is RNH under-performing relative to his pay and role? If so, then the team needs to move on. Full stop. In a flat cap world, you can't afford to over-pay for underproduction (or even stagnation). Doing so leads to less winning, which leads to the doomsday scenario you're worried about. It's clear in Year 10 of his career that RNH does not have another level to his game, so signing him to even the same amount of money is just as damaging as giving him a raise.
You can try and dispute that with more arguments about how he's good in the room and deserves it for being a good soldier through all the bad, but none of those things makes us better and so that's where the discussion should rightfully end.
It's about communicating the plan. Knowing there is a plan. The fact is there is a relationship between these players, there's trust. Of course players know trades, free agency and movement is part of the business. All will move on if Nugent Hopkins isn't signed. It's still about managing the relationships with your best players and engaging them to understand the plan which leads to winning hockey games and competing for Stanley Cups. Players get behind a vision and today's athlete is different than past generations who mainly complied without question on things. There have been many plans in Edmonton for the last fifteen years and very little success. Now breaking through (it seems) engaging your leaders to communicate the plan is reasonable and respectful. Understanding and buy-in is helpful to ensuring everyone is on the same page, understands, and move forward united.
I think Nugent Hopkins is a versatile, valuable player. His goal and point production the past three years has been strong and worthy of his salary. He plays big minutes (20 per game) in all situations. And has produced with Draisaitl which included a Hart Trophy win and produced in play-in with McDavid. As a 2C option, he is asked to play with rotating wingers which has mixed results. I think this team is better with Nugent Hopkins resigned than letting go for nothing. I don't believe he is easy to replace. But I also don't think it is resign at any cost. As you've alluded to my postings you'll see my ceiling has been $7 million/season. Last reporting we've had is it is likely being negotiated in the $6-$6.5 million/year range. This is a tricky negotiation and I trust the players involved (as I've also stated throughout) Ken Holland and the player to arrive at fair market value in a tough cap year. If they don't, I will be interested in seeing how this team replaces the utility that Nugent Hopkins brings.
But we can all play GM and are in thinking we know the value or not of this player, to this team, and in this market. You've made your conclusion and I've stated my hope this player re-signs for reasonable dollars and term in Edmonton. There's a lot of well researched posts that give us market value comparisons throughout many threads. I find them helpful.
Regarding good in the room and good soldier stuff, I really defer to what his GM's, coaches have said about the player and what we hear from his teammates. I'm not in the room so that's as close to it that I can get. I guess they could uniformally be pumping tires but I don't really see any reason to think so.
EDIT: Re-read your post and not sure why you think Nugent Hopkins would be traded (presume you think this as a deadline deal)? This is being reported as likely being negotiated through to first day of UFA vs a dump on team pushing for a playoff run. Most likely scenario is no deal player hits UFA and return on investment is zero.