I think that you have captured the essence of these complex issues and the questions you continue to ask show that you are grasping the concepts well.
So far, I have not yet seen any court reach a determination that a mortgage granted in favor of MERS is actually itself void or a nullity, nor would I expect a court to reach such a result.
It is probably appropriate to note that there are two ways that MERS can come to call itself the "mortgagee". First, an originating Lender or a subsequent holder and assignee could grant a mortgage assignment in favor of MERS. Second, MERS may be designated as the mortgagee in the original instrument.
In its infancy, most of its mortgages were the former, but as MERS matured, most of its new business came from mortgages naming MERS as the mortgagee in the original security instrument. These latter types of loans are sometimes called "MOM" loans, standing for "MERS as Original Mortgagee".
Think of the recent Oklahoma appellate decision in BAC Home Loans v. White. In that holding, the Oklahoma court stated:
". . . In Oklahoma, ownership of the note is controlling, and assignment of the note necessarily carries with it assignment of the mortgage. Gill v. First Nat. Bank & Trust Co. of Oklahoma City; 1945 OK 181, 159 P.2d 717, 719. "The mortgage securing the payment of a negotiable note is merely an incident and accessory to the note, and partakes of its negotiability. The indorsement and delivery of the note carries with it the mortgage without any formal assignment thereof." Prudential Ins. Co. of America v. Ward, 1929 OK 71, 274 P. 648, 650. Proof of ownership of the note is proof of ownership of the mortgage security. Engle v. Federal Nat. Mortg. Ass'n, 1956 OK 176, 300 P.2d 997, 999. Therefore, in Oklahoma it is not possible to bifurcate the security interest from the note. An assignment of the mortgage to one other than the holder of the note is of no effect."
The court then simply applied this rule to the facts of the instant case, reversing and remanding without elaborating in any way as to precisely HOW this would effect upwards of 100,000 other MERS mortgages.
If it is not possible to bi-furcate a loan in Oklahoma, then it would seem that all of the express assignments INTO MERS would be nullities absent the negotiation of the note to MERS. And similarly assignments OUT of MERS would also seem to therefore be nullities.
The effects of the decision on the MERS "MOM" loans is a little less clear. Does the decision mean that the original named Lender is the mortgagee and the designation of MERS in the MOM instrument is a nullity or does the MERS as Original Mortgagee language actually poison the original security instrument.
The Court tells us that the mortgage security instrument follows the note in Oklahoma, which has been the common law rule for several centuries. If the mortgage is actually valid, as you propose then the proper negotiation would carry with it the mortgage lien. But the negotiation needs to be proven.
You need to bear two thing in mind in assessing the implications of this particular ruling (which is authoritative ONLY in Oklahoma, though there are similar rulings elsewhere).
First, bear in mind that a principal purpose of the forged assignment is for use as fabricated evidence and false proof in judicial foreclosures or to create a false record in support of a trustee's deed in deed of trust states. When you eviscerate the legal viability of this forgery, either by showing it to be a forgery or showing that such an assignment is a nullity as a matter of law, then a critical piece of the plaintiff's proof disappears.
The second critical thing to bear in mind is that the forgery of the assignment itself is good defensive evidence for use in either a clean hands equitable defense or in seeking sanctions. The former is generally more potent than the latter. I have discussed this before in other threads.
A challenge the borrower now faces is that the mortgage servicer will now seek to present other alternative evidence to the court in support of foreclosure. Given the identity of the plaintiff and Countrywide/BAC's record of evidence fabrication and makig false statements under oath, the defendant WHITE has more than a little reason to be concerned.