Where would a Steem dump come from and for what purpose? If it's from speculators then of course it could happen but I expect Steem to act more like Bitshares used to act. There was a slow dilution of Bitshares over a period of many months but that happened because the userbase of Bitshares wasn't growing at a rate fast enough to support the dilution.
In this case there is plenty of demand for Steem, Steem Power, Steem Dollars, and each new user increases demand for all three.
I mean I think it's natural for all assets that can be converted into cash to be heavily sold at some point, could just be that a holder cashes out. The dump would actually be a result of the panic selling by emotionally engaged traders.