Following her husband's death, Mary became the sole owner of numerous highly valued properties throughout Europe and North America. Had she simply sold each of these properties one by one, Mary would have had more than enough money to live out her years in complete luxury, and there would have been plenty of cash left over for her two (worthless) children.

Unfortunately, Mary took to the bottle and to gambling. Within a few years, Mary was left nearly destitute after gambling away most of her inheritance.

However, by some miracle, Mary somehow managed to retain ownership of a beautiful townhouse in Manhattan, as well as a plot of land somewhere in Florida. Mary had no interest in some "mosquito-ridden frog bog" in Florida, but she did take an interest in the townhouse.

The townhouse was located on the Upper East Side. Despite needing new furniture and a good cleaning, the building itself was in fine condition. An appraiser valued the property at approximately $4,500,000, so this was an overall great piece of real estate.

Mary decided to move into the townhouse and live out the remainder of her life there. Using whatever cash money she had on hand, Mary furnished the townhouse and hired a housekeeper. Since Mary had no income source, Mary took in a tenant who lived in the basement of the townhouse. From these rental payments, Mary was able to finance her new modest lifestyle.

After some time, however, Mary's health took a turn for the worse.

Naturally, being in failing health, Mary had to decide what would happen to her real estate after she died. Being partial to boys, Mary wanted to leave the townhouse to her son, John. Her daughter, Molly, could have the land in Florida.

One month before her death, Mary decided to execute a quitclaim deed transferring title to the townhouse to John. Mary's lawyer prepared all the paperwork, and he instructed his (stupid) paralegal to take the deed to Mary's townhouse to get her signature. Once she signed it, the paralegal was instructed to leave the deed with Mary who would give it to her son.

When the paralegal arrived at Mary's home, Mary had been drinking heavily. It took a few minutes, but Mary did manage to sign the deed. The paralegal then left, leaving the deed with Mary as he was told.

Since John was somewhere in Europe at the time, Mary handed the deed to her housekeeper for safekeeping. Not knowing what to do with a deed, the housekeeper placed it in the cookie jar and soon forgot about it.

The next day, Mary called Molly and told her that the plot of land in Florida was "all yours." Mary continued the conversation by ordering Molly to "go take it before your father turns it into a parking garage."

Molly was startled by this statement. She reminded her mother that her father had been dead for several years now.

"Oh yeah," replied Mary. "I forgot."

Before continuing the conversation, Mary barked out an order to her housekeeper to bring her some more wine. After a few sips, Mary informed Molly that the townhouse was given to John one day earlier.

Molly was furious at this revelation and became emotional.

"OK, OK" interrupted Mary. "If you want this old house, you can share it. What do I care anyway? I'll be dead. Just shut up!" Mary quickly promised to amend the deed she had executed the previous day, and hung up the phone. She then finished her wine and went to bed.

The next day, Mary called for her housekeeper to bring her the deed, but the housekeeper had gone homesick. Severin knew the housekeeper had hidden it somewhere in the kitchen, but she was not sure where. After a few minutes of searching, Mary became frustrated. Before reaching for a new bottle of wine, Mary called her lawyer.

Unfortunately, the lawyer had gone on vacation, so Mary got stuck speaking to the (stupid) paralegal. She told the paralegal that she wanted to execute a second quitclaim deed naming both John and Molly as co-owners of the townhouse.

Wanting to be helpful, the paralegal quickly ran over to Mary's townhouse with a new quitclaim deed for her to sign. After Mary signed the second deed, she instructed the paralegal to mail it to Molly so that her daughter would "shut up and stop complaining." Molly received the deed the next day.

A few weeks later, Mary died.

After Mary's funeral, while going through his mother's possessions, John discovered the first quitclaim deed in the cookie jar. Later that day, the housekeeper told John about the phone conversation between Mary and Molly in which Mary decided to amend the deed.

John became furious with his sister. He accused Molly of manipulating their mother. The following day, John filed a lawsuit against Molly for full ownership of the townhouse.

My question is:

What is the most probable outcome of John's lawsuit?