Ah but see, this answer exposes the weakness in your position. It is what is referred to in scholarship as an unnatural reading of the text. The passage reads as a continuum.
28 And it shall come to pass afterward, that I will pour out my Spirit upon all flesh; and your sons and your daughters shall prophesy, your old men shall dream dreams, your young men shall see visions: 29 and also upon the servants and upon the handmaids in those days will I pour out my Spirit. 30 And I will show wonders in the heavens and in the earth: blood, and fire, and pillars of smoke. 31 The sun shall be turned into darkness, and the moon into blood, before the great and terrible day of Jehovah cometh.
Taken together here, the implication is that the signs and wonders that take place in the heavens and on earth will be prophesied by those upon whom He pours His Spirit. If you read v.28-29 as being fulfilled 2,000 years ago, but v.30-31 as not destined to be fulfilled until thousands of years later, you have this bizarre interpretation of the passage that disassociates the wonders in the heavens and on earth from those who will proclaim them in advance to the nations.
Let me show you another unnatural reading you are subscribing to. You were saying that the only "prophets" in the end-times will be the two witnesses. But in Revelation we read the following:
23 The light of a lamp will never shine in you again, and the voices of a bride and bridegroom will never call out in you again. For your merchants were the great ones of the earth, because all the nations were deceived by your sorcery.” 24 And there was found in her the blood of prophets and saints, and of all who had been slain on the earth. (Revelation 18:23-24).
Now, if the two witnesses are the only prophets who will exist during this time, you have "prophets" here referring to only two people, and this would lend itself to interpreting "saints" as only a few as well. If not, you have again an unnatural reading of "there was found in her the blood of many saints and two prophets." It doesn't read naturally. If, however, you understand it in the context of Joel 2:28-31, it makes perfect sense. There will be both many prophets and many saints during the end-times, and they will expose the false church for her wickedness and proclaim judgments upon her. As a result, the false church will murder them.
Another question in this regard is this: When and how will it be fulfilled the scripture that says the saints will do even greater works than our Lord did?