My view of what may have happened is always tempered by my belief that Caesar had no intention of instituting a permanent autocracy, and that the position of Dictator for Life was just another one of the excessive honours heaped upon Caesar by the Senate (for what purpose they did this is the subject of another debate), and that Caesar didn't stand in their way because there really wasn't any need to. Sulla had, essentially, made himself Dictator for as long as he cared to be, so Caesar could have viewed being made Dictator for Life simply as a way of preserving his Dictatorship until whenever HE was good and ready to give it up, without having to go through all the bother of getting himself reinstated whenever his term should technically have ended according to the old rules.

As to the heading off for Parthia: I've always thought of Caesar as a liberal conservative reformer (if there is such a beast!) rather than a radical or a revolutionary (in my opinion there were very few true revolutionaries produced by the Roman aristocracy: they generally only ran from liberal conservatism to die-hard reactionism). If you look at him in that light it probably explains why he didn't make sweeping changes to the Roman system of government during his Dictatorship: he wanted to sort out the practical faults of the existing system, rather than create something new. In this way, having made the sorted out the majority of the practical problems, heading off to Parthia would put sufficient distance between himself and Rome and the Senate for its members to exert more of its traditional independence, whilst still being able to oversee things from afar. He probably expected there to be a few teething problems, but wanted the Senate to try and deal with them itself, and, if they couldn't, he would be able to sort them out when he came back.

Then, when the 'Parthian equation' was sorted out (and I doubt that meant outright conquest) he could return, set what needed to be set aright, and would have abandoned his Dictatorship in much the same way as Octavian divested himself of his (technically lapsed) triumviral powers. After that he would assume the position that he always seemed to genuinely want: that of the First Man in Rome - perhaps in a slightly more formal guise than had hitherto been the case. Cicero had been talking for over a decade about how the Republic needed a guide, and Caesar would command the necessary dignitas, auctoritas, and ability to fit the bill (he would also have what was Augustus's ultimate power base: the loyalty of the legions).

Oh, and I admit that much of this is supposition! *G*