From what I've heard from a former colleague of Dimon, his minions will have thoroughly investigated and assessed Michael Willingham and concluded that he is a formidable adversary. Accordingly, they know that he won't fold for $8.
The only way to neuter him would be to offer something that is sufficiently close to what he wants such that other members of the board will be tempted to pressure him from within.
Taking your $48 number as a hypothetical, a $38 offer might do the trick. It would certainly tempt some board members who would argue that accounting for the time value of money, $38 today is better than $48 a year or more from now.
Weil/WMI are going through the motions as they know they've lost control of the plan process.
The only real uncertainty for equity at this point is whether (1) a shareholder meeting can be held (depends on a WA state court ruling) and (2) if so, there are sufficient votes to replace the current BOD.
JPM knows that if the BOD is changed litigation will be renewed with fervor (i.e., depositions will be taken). It could wait for the state court ruling to make a real offer (and I believe it will) or brazen it out until a new BOD is actually installed. In either case it would have to make such a tempting offer to common (on a drop dead basis) that the EC would be under tremendous pressure to accept. If I had to be, this is the most likely outcome as I don't believe JPM will ever submit to real discovery.