Well, we seem to have too many NHL forwards on the roster at the moment, so there exists the possibility that Pageau starts the season in Bingo because he is waiver exempt.
10 forwards: Spezza, Michalek, Turris, Smith, Neil, Greening, Condra, O'Brien, Kassian and Alfredsson (if he comes back for another year) are all on (or will be on, when they sign) one-way contracts
The guys who are waiver exempt who for sure aren't going back to the AHL are: Zibanejad, Silfverberg, Conacher
... so that's like 13 forwards right there without even considering Pageau. Add to that the fact that Murray has heavily hinted that Hoffman will probably be on the team in some capacity next year, and that Mark Stone could conceivably make the Sens next year, and you start to see the problem. If we don't make a quantity-for-quality trade before the season starts, Pageau's contract and waiver exemption will probably keep him in Bingo to start the year, despite the fact that skill-wise, he's ahead of guys who might make the team in October.
I think the better question is do we think that Pageau will be on the roster by the end of the season, not the beginning of it. And the answer to that, at least for me, is "yes".