“Will we ever receive more scripture?” New Era, April 2016, 41
First of all, there are two definitions of “scripture.” On the one hand, “whatsoever [the Lord’s servants] shall speak when moved upon by the Holy Ghost shall be scripture” (D&C 68:4). This could include things taught by prophets and apostles in general conference, and we are receiving that kind of “scripture” continually.
On the other hand, there is scripture that is officially recognized and added to our books of scripture (what we call “the standard works”). From time to time, the Church authorities will decide to add something to the standard works and present it to the Church for acceptance (see Bible Dictionary, “Canon”). This may not happen frequently, but “we believe that [God] will yet reveal many great and important things” (Articles of Faith 1:9), including things that may be added to our books of scripture. Whether scripture of this kind is added depends on the Lord’s timing, as well as our faithfulness.
We also know that many ancient scriptures we don’t currently have will eventually come forth. Some of them may come forth when we’re ready to receive them—for instance, the sealed portion of the Book of Mormon (see Ether 3:27; 4:6) and the “fulness of the record of John” (D&C 93:18). At the latest, this will happen at the time of the Second Coming, when “all things which have been revealed unto the children of men shall … be revealed” (2 Nephi 30:18).