Does present-day prophetic ministry challenge or undermine the sufficiency of scripture?

Of course not.

The canon is closed - no more scripture is being written. The Bible is the authoritative standard by which anything prophetic should be measured.

But in the Bible there have always been prophets and prophetic ministry that did not result in the writing of Scripture - prophetic utterances that may have been timely in the moment, but were not timely forever. Genuine prophetic utterances that were not recorded as scripture. Is it really so hard to believe that this type of ministry is still present today?

Moses had 70 elders that prophesied, but whatever they said was not recorded as scripture. (Num. 11.25)

King Saul and his men all prophesied, but whatever they said was not recorded as authoritative. (1 Sam. 10 and 19)

The Tabernacle of David (1 Chron. 15-16, 23, 25) was a tent, erected by David - before the Temple was built - where about 4,000 musicians and 288 singers were employed to sing and prophesy. Aside from possibly a few Psalms, their words were not recorded in scripture.

Elijah and Elisha had an entire school/company of prophets (1 Ki. 18, 2 Ki. 2, 4, 5, 7) that they trained and developed in this ministry - most of which resulted in no scripture being written.

The church in Antioch had prophets (Acts 13), but aside from Paul, we know that none of them wrote scripture.

Philip the evangelist had four daughters that prophesied (Acts 21.9), not one of them penned an epistle.

Evidently it has always been the case that not all prophecy resulted in the writing of scripture. In fact, it's probably likely that MOST prophecy has not resulted in the writing of scripture.

If it was possible for people to prophesy in both the Old and New Testaments without it resulting in new scripture being produced, is it really that hard to believe that God couldn't still use people to prophesy today, without new scripture being produced?

"True prophecy is a perpetual ministry in the New Testament church. It is nothing less than receiving the Spirit of God and giving forth the messages of God to men under His inspiration and power. This does not mean new messages of authority in addition to the Holy Scriptures, but it does mean the Holy Scriptures themselves interpreted and applied under the quickening touch of the Spirit of God." - A.B. Simpson (Christian and Missionary Alliance Weekly; "The Anointing"
May 23, 1908. Pg. 130)

I am convinced that the most abused and misused spiritual gifts in the church are the gifts of leadership and teaching. Yet, most Christians are willing to look past the abuse of these gifts because they also see the transforming benefits of these gifts in their own lives, when exercised properly. They know that it's "worth the trouble."

When people begin to see the significant benefits of spiritual gifts like prophecy, tongues, discernment, healing, etc. - and that they are "worth the trouble" I believe that they will be willing to sort through the mess of the abuse and misuse in order to identify the correct use of these gifts.

When a person experiences the ability of all of the gifts to strengthen, encourage and comfort it becomes far more difficult to dismiss them.