I think a main problem with traditional Gush lists right now is that the metagame is not friendly toward cantrip-based decks. A year ago, things were much better for Preordain et al. I discussed this in more detail in the Ritual Oath thread.
There is a lot of truth in that statement. I have been running Gush for over a year now, and since February, I have had consistently mediocre to bad results with it where previously, I had done quite well in terms of at least being in contention well into the late rounds of nearly every tournament I had played in. That's not to say I don't think Gush is not viable, as decks like RUG Delver and Turbo-Tezz have put up good results, but neither of those was a "conventional" Gush deck, but rather used Gush as an efficient draw mechanic, and not an engine for the deck, like East Coast Wins or Rich Shay's Champs list from last year did.