Luther believed prophecy to be active today:
"Astronomy, on the contrary, I like; it pleases me by reason of her manifold benefits. General prophecies and declarations, which declare generally what in future shall happen accord not upon individuals and particular things" (Table Talks, Of Astronomy and Astrology, DCCXCVIII).
In regard to the German, the quote was probably taken from a source similar to Dr. Martin Luthers Sämmtliche schriften, Volume 22, 1550. Both sentences are separated by a fair amount of text, including a sub-heading. The first line is "Astronomiam nehme ich an, und gefällt om wohl umb ihres mannigfältigcn Nutzes willen." The second line further down is "Gemeine Weissagungen und Verkündigung, da man etwas insgemein zuvor verkündiget, wie es ergehen soll, reimet noch zeucht sich nicht auf einzelne und sonderliche Dinge und Personen."
This quote as it's been cited in English above was taken from an early English edition of the Table Talk. The version being used appears to be from a later reprint of the Hazlett edition (also found on the CCEL website). The number DCCXCVIII appears to be a later renumbering of the earlier edition. Earlier editions number this entry DCCCXLII. I'm absolutely certain the quote as it's cited above and found in early Hazlett editions is an edited version of a much lengthier utterance in English from Luther on Astrology. The unedited English can be found here starting at the bottom of page 309. Compare this with other later English editions.
An astrologer and a star-peeper, is to be likened to one that selleth dice, and saith, Behold here I have dice that always run upon twelve; the rest of the fifty casts, they run upon two, three, four, five, six, seven, eight, nine, ten, eleven. Even thus it is with the astrologers; when once or twice their conceit and fantasies do hit, then they cannot suficiently extol and praise the art; but touching the other so often failing, of the same they are altogether still and silent. I accept of astronomy (said Luther), it pleaseth me well for the sake of her manifold profits. David, in the 19th Psalm remembereth the wonderful works and creatures of God in the firmament of heaven, he taketh therein his delight; Job also remembereth Orion, which they call Jacob's staff, the seven stars, &c. To conclude, the example of Esau and Jacob maketh astrology merely a juggling and confounded work, therewith the astrologers always have enough to do to plaster themselves.
Concluding arguments against Astrology.
First, that doctrine which dealeth and handleth a matter is uncertain; for materia est informis, is without shape and form, without any quality and fitness; the doctrine of the astrologers and star-peepers dealeth and handleth touching matters, therefore astrology is uncertain. Secondly, General prophecies and declarations, when they will declare a thing generally before what in future shall happen, neither do accord nor draw themselves upon singular and particular things or persons; non competunt specialibus & individuis, they agree not to specials and individuals; but the astrologers and star-peepers do teach general predictions and presages which cannot be directed to and upon particular things and persons, therefore the astrologers and star-peepers do wrong, in drawing and directing there predictions to and upon particular and certain persons and things. Thirdly, When at one time many are slain together in a battle, are shot, struck dead, &c. No man can truly affirm, that they were all born under one planet, yet they die altogether in one hour, yea oftentimes in one moment, especially before the mouths of great cannon and ordnances.
Even without the extended context, the subject matter of the truncated quote is about astronomy, not prophecy. I can see though how someone not being careful read the sentences as the separate subjects of astronomy and "general prophecies and declarations." In context, the comparison is between astrology and astronomy, and that Luther rejected the former and was pleased by the later. Then, the second sentence appears in the next section under the concluding arguments. The "General prophecies and declarations" are in regard to that put forth by astrology.