I can't see why. I'd be shocked if she did not.
1) At some point in time Hillary is going to have to decide if she is going to run for President. All of us believe there is absolutely no doubt Hillary will run for the Presidency in 2008. What will the impact on Hillary's Senate run be if she announces her intention to run for the presidency during her Senate campaign? What will the impact on Hillary's run for President be if she announces during her Senate run her attention to serve a full term but reneges on that promise?
2) What if Hillary wins the Senate race but falls far short of her predicted margin of victory expectations? A close race in New York, an extremely liberal state, means Hillary has huge problems in a national election. It seems far more logical for Hillary to announce her intention to seek the presidency in 2006 as a reason for foregoing the Senate run.
3) If Hillary were to lose her Senate seat, no matter how slim the possibility, 2008 is over.
4) What will happen if Hillary decides not to run and a Republican wins the US Senate race in NY?
5) Running for the Presidency as a Senator is almost an impossible approach for winning. Hillary as a Senator will have a Senate voting record to defend. She will not only have to defend that voting record against Republicans but also against Democrats. Why not let the opposition (mostly Senators from both parties at this point) have records to defend while you concentrate full time on your presidential campaign a year before anyone else and not have a Senate record to defend later?
6) What if the Republicans increase their majority in the Senate in 2006? What is the value of remaining in the Senate for Hillary or any other Democrat seeking the Presidency if this happens? IMHO a Hillary Senate run is not a sure thing.