This is one of those scriptures that a Christian can get out of it what he takes to it. There have been many innovative interpretations of this scrppture so that people can get out of it what they want it to mean. This includes famous preachers, theologians, etc.
My interpretation is that it was sent to Jews that rejected Judaism by becoming True Christians and were being pressured by the unconverted Jews and family to return to Judaism. It was a warning that if they publically rejected Christ and returned to Judaism, they would find it impossible to be convinced to return to Christ. It does not mean that God would not take them back again, but that it would be impossible to convince them to return to Christianity because they would consider themselves mocking Christ.
I think my interpretation is different that any you listed above.
Bingo. And that conclusion is one that best suits the immediate context and historical context. The latter half of the 10th chapter through the end of Hebrews contain many good warnings and exhortations to these Jewish Christians to continue in the truth. Really, that's what the whole book of Hebrews was intended to accomplish: to show that Christ and the new covenant were better than what came before and thus we should continue in them.