Eli will want a $20 handle on the price otherwise he looks like the chump that he has proven to be.
Shareholders will be happy with $18 if it came to a vote.
To avoid a nasty battle with Eli, Samsung will have to offer around $20, IMO. They will want key individuals to stay for a while so a nasty takeover is not a realistic procedure.
Samsung has to offer $20 and generous severance (golden parachutes) to management to make this deal work. And they better offer it soon before the market bounces up. If the Nasdaq goes up 10%, Samsung will have to offer 10% more.
Lower Nasdaq prices makes the takeover of Sandisk more likely, albeit at lower prices.