I think there will be a dump of the ETC by the big holders as well as the DAO hackers, then attack will begin then.
Part of your theory makes no fucking sense... and so seems like you are trying to dream an outcome based on erroneous understanding of motivation.
Think about it?
Why would the DAO hacker dump ETC? We should assume that he wants the price to go up and also to get as much as he can... or at least for the ETC chain to stay alive...
I agree that the big ETH holders may have an incentive to dump ETC, but even their motives are going to be mixed, especially if the ETC buyers are able to absorb the dump.. then they run out of coins to dump.