abe,
When "the 70 week prophecy itself mentions the Messiah", it is not speaking of the NT's Jesus Christ.
A "messiah" was any person anointed with oil or grease either as a (military) king or as the High Priest. Hence the Babylonian exiles considered Cyrus to be a Messiah. Hence the Jews at the time of Jesus expected that the Messiah would inspire and lead a military uprising that would remove the Roman yoke.
The "70 Weeks" has been subjected to repeated reinterpretations from the time it was first written. At the time of the NT it was still seen as eschatological. Hence the gospel writers, who had just witnessed the destruction of Jerusalem at the hands of the Romans, applied the predition to that event. No NT writer applies the "70 Weeks" to Jesus Christ.
Centuries later, the Christians changed their position and they started to apply the "70 weeks" historically, with most - but not all - relating it to the ministry of Jesus Christ.
Thus your idea that the "70 weeks" should be understood eschatologically is in line with the style of understanding at the time that the NT was being written. But by the time that the NT Canon was set in the 4th century, the understanding had gone through a great change and was interpreted by most as historical. Of course, as I said, not all those historical interpreters referred the "70 Weeks" to the timing of Jesus Christ's ministry.
Doug