All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
It is too early to ask about this and it should not be a reason for dispute between you and your in-laws (the family of your wife). Our life is in the Hands of Allaah and you do not know who amongst you would die first.
If we presume that your wife dies first and she has no children from you or from anyone else, then you are entitled to one-fourth of her inheritance. In addition to this, the money that she gifted you while she is in good health and in sound mind and you possessed it [gift], then it is yours as well. Therefore, if she had gifted you a land or a house as an effective gift that is not conditioned upon her death, and you possessed it before she dies, then it will be only yours and no one else among her heirs would share it with you. As regards writing the house or anything else in your name so that you would possess it after her death, then this is of no effect because it is a will for an heir and it is not valid unless all other heirs agree to it.
As regards investing in the land with the permission of your wife, then this does not make you the owner of the land; rather, you should benefit from it according to the permission of your wife, but if the right (the ownership) is transmitted to others, then that permission becomes void, in which case, other rulings apply, but this is not the place to mention them.
However, you may in that case give compensation to the rest of the heirs for their right in that land so that this land will become only yours.
This is of course based on the assumption that your wife dies before you and before her heirs, and this is a matter pertaining to the unseen.
Allaah Knows best.