Summarized, here's the new Tyranid rumors to come out of Gamesday Italy:
Plastic Trygon (no confirmation on whether it's Apoc or not)
None of the current plastics are being redone (I heard this one a few months ago).
Some metals will be made plastic (My guesses are Gargoyles first, Tyrant second).
I was personally hoping for more, but it seems GW is running a tight ship these days. Of all the things, I am really hoping for the plastic Trygon. People are saying that they won't ever put an Apocalypse unit into a regular codex; but what of the Valkyrie? They simply modified some rules and it works perfectly in-game. Also, a Trygon is hardly Apocalypse material. It is overpriced and very vulnerable. You can make a Carnifex just as tough, with a better save and for half the cost.
Some people say that they won't put a Trygon in the codex because it's too big. However, it's only about the size of a drop pod. I of course would be a very happy hive node if the Trygon made it into the codex. Even if it was a 0-1 restriction I would still buy three.
Of course none of this is fact yet. Just because someone higher up said it at Gamesday and said quote made it on the interwebs, doesn't mean it's true. All we can do is wait for the inevitable leak, or until GW decides to impart their knowledge unto us.
Update: Gaunt boxes have been pulled from the GW store. Does this mean they'll be splitting the contents? Rumors suggest the base box size will go up to 10 models, but they'd have to re-do the sprue if that was the case.