I don't use back doors; it's the front door or no door for me. For me, and for the saints of old through 18 centuries of Church history.
Actually the very oldest comments we know about concerning this, say the very opposite to what you claim.
The very oldest Christian commentary in Bible prophecy (of any significant length) that has survived to the present day, said, concerning the Antichrist whom he taught would come in the future, “And then he points out the time that his tyranny shall last, during which the saints shall be put to flight, they who offer a pure sacrifice unto God: ‘And in the midst of the week,’ he says, ‘the sacrifice and the libation shall be taken away, and the abomination of desolation [shall be brought] into the temple: even unto the consummation of the time shall the desolation be complete.’Now three years and six months constitute the half-week.” (Against Heresies, by Irenaeus, book V, chapter XXV, section 4)
This work, which is believed to have been written between 186 and 188 A.D., in quoting Daniel 9:27 when speaking about the future, was plainly teaching that it remained to be fullfled in the future.
But less than 30 years later, in the very oldest Christian commentary on scripture (as opposed to a commentary on a scriptural subject) that has survived to the present day was written by Hippolytus This is a commentary on the book of Daniel which is believed to have been written between the years 202 and 211 A.D.
Hippolytus said:
“For after sixty-two weeks was fulfilled and after Christ has come and the Gospel has been preached in every place, times having been spun out, the end remains one week away, in which Elijah and Enoch shall be present and in its half the abomination of desolation, the Antichrist, shall appear who threatens desolation of the world. After he comes, sacrifice and drink offering, which now in every way is offered by the nations to God, shall be taken away.” (Commentary on Daniel, by Hippolytus, book 4, 35.3)
Hippolytus returned to this subject some pages later, writing:
“Just as also he spoke to Daniel, “And he shall establish a covenant with many for one week and it will be that in the half of the week he shall take away my sacrifice and drink offering,” so that the one week may be shown as divided into two, after the two witnesses will have preached for three and a half years, the Antichrist will wage war against the saints the remainder of the week and will desolate all the world so that what was spoken may be fulfilled, “And they will give the abomination of desolation one thousand two hundred ninety days. Blessed is he who endures to Christ and reaches the one thousand three hundred thirty-five days!” (Commentary on Daniel, by Hippolytus, book 4, 50.2)
So forget the nonsense that the notion that the 70 weeks have all been fulfilled was taught by "the saints of old through 18 centuries of Church history."