I wouldn't want to trade Cholowski at this point. Especially considering that the hypothetical trade would be for the opportunity to draft a Dman that is younger and possibly not as close to making an NHL impact as Cholowski may or may not be at this point. On top of that, if the Dman taken at 10OA doesn't pan out as a top 4 but Cholowski pans out as such in Edmonton, the trade ends up looking real bad down the road.
If they were to make that kind of deal, I'd rather it go in the other direction and bring in a young Dman ready to step into a top 4 role.
As for Nyquist, there's a few things to consider. Would he waive his NTC to go to the Oilers? Unless Peter Chiarelli is offering up a nice NMC laden buyout proof 7/8 year deal, Edmonton isn't exactly a top destination for players. Then again, the incentive for Nyquist would be that he goes there and plays on a line/PP with McDavid, gets closer to or exceeds 30 goals/60 points and then hits the UFA market looking for $6M+ with term. For the Oilers, they'd have to be OK knowing that there's a strong possibility Nyquist would walk next summer. Then again, if the hypothetical stat padding happens but they are out of the playoff picture, they could likely get a decent return for Nyquist at the deadline.
I think a more attractive winger to offer the Oilers would be AA. He's still only 23 and may still have upside and/or might benefit from a change of scenery. He's also not eligible to hit the UFA market until the end of the 21/22 season, so he could potentially be a cost controlled option that could be with their team for at least the next 4 seasons.
That said, I doubt AA and Cholowski is enough to get 10OA from them, especially if what they are really after is an established top 4 D.