Quite possible. I assume that when Anne dies, William and his son becomes co-monarchs, and when William dies, his son becomes the sole King.
The full text of the Act of Parliament accepting William and Mary to the throne can be
found here. The relevant passage is:
Having therefore an entire confidence that his said Highness the prince of Orange will perfect the deliverance so far advanced by him, and will still preserve them from the violation of their rights which they have here asserted, and from all other attempts upon their religion, rights and liberties, the said Lords Spiritual and Temporal and Commons assembled at Westminster do resolve that William and Mary, prince and princess of Orange, be and be declared king and queen of England, France and Ireland and the dominions thereunto belonging, to hold the crown and royal dignity of the said kingdoms and dominions to them, the said prince and princess, during their lives and the life of the survivor to them, and that the sole and full exercise of the regal power be only in and executed by the said prince of Orange in the names of the said prince and princess during their joint lives, and after their deceases the said crown and royal dignity of the same kingdoms and dominions to be to the heirs of the body of the said princess, and for default of such issue to the Princess Anne of Denmark and the heirs of her body, and for default of such issue to the heirs of the body of the said prince of Orange. And the Lords Spiritual and Temporal and Commons do pray the said prince and princess to accept the same accordingly.
So if William and Mary have surviving issue, then William becomes sole monarch upon Mary's death (assuming she predeceases him as per OTL), and their child succeeds only once both William and Mary are dead.
An interesting tidbit I'd not been aware of before is that if William had remarried and had children by his second wife, those children too would be in the line of succession, but only after Anne.