Start with RR or Dahlin

For Hall? RR sure. Dahlin? You're even higher than the guy proposing these trades.

Buffalo will not trade Dahlin, especially Hall from one year UFA, closer will be the trade of EK in San Jose.

For Hall, 2020 2nd, 2021 3rd, 2021 6th and Asplund?

Realistically, you're looking at Risto, Rodrigues, Nylander, 2020 1st (or 31 OA in 19) for Hall. I pass personally unless I know he's resigning.

No, well, this will not be enough, look at the deal Karlsson.

I agree, I pass unless I knew I could sign Hall. That may be the asking price but then Buffalo needs to find a RHD, an energy 3rd line winger, a still decent prospect and an early 2nd. I would pass on getting him.
I am spit ballin' here, what is the difference value between Adam Larsson and Ristolainen?
I know, that is what Betterall gave up for Skinner in a similar situation. Since Hall is better, i offered a better prospect.

Ristolainen has to be worth more than Larsson. No matter what all his detractors will try to tell you. In league circles hes valued higher I'm pretty confident in that. Or at the very least he should be.

This was obviously a tongue in cheek comparison of the Skinner trade.
Here is the problem, in two years Dahlin, Hall, Eichel, Skinner, Reinhart, and Montour ($12,000,000, $10,000,000, $10,000,000, $9,000,000, $7,000,000 and $7,000,000 respectively) will consume over half of the Sabres cap. So let's say $30,000,000 will be divided among 14 players. In two years, I would imagine if they played well, Pilut and Mittelstadt would be looking to get something north of $5,000,000 leaving $20,000,000 only for 12 players.
While the Sabres would have a really good top line, they would be the Oilers a team with out any depth.

Yes, it doesn't make sense for the Sabres but the long term plan may be a trade of Reinhart or even Mittlestadt, so you never know. There's ways to make it work.