There is a chance of course, but it is very low.
The mid-year report gave us some valuable information in this regard:
http://www.cic.gc.ca/english/resources/reports/ee-midyear-2015.asp
At the current frequency and number of ITAs per draw, it is unlikely that the score will drop way beyond ~450. This seems to be the rough equilibrium for the number of ITAs per month and the monthly pool growth rate of ~6,000 profiles.
In the first half of 2015, CIC have invited ~12,000 candidates. As explained above, if they invite the same amount in the second half of 2015, scores will not drop significantly (provided the pool growth rate and the score distribution of newcomers stays roughly the same).
For the scores to drop to 400 by the end of this year, CIC would have to invite at least 8,770 candidates in addition to the 12,000 mentioned above. This is because there were 8,770 candidates between 400-449 points. In reality, the number would have to be even higher because this bracket will also keep growing through the rest of the year.
So, realistically, unless CIC basically more than doubles the number of invitations for the rest of the year, scores will not come down to 400 points.
There is a possibility for program-specific draws and scores might drop further for specific programs if the score distributions is vastly different among the programs (but we don't have any information about this).