Some of this old and been posted here, as it is a compilation of things Stickmonkey has said recently, and a few that were said some time back. Check out the rumor, and enjoy. As with any rumor, please take with a grain of salt.
via Judas Masias,
I found this Stickmonkey:
Lots of internal rumbling on a 2nd wave of tyranids. I don't have timelines, but expect it to hit before end of year, but after dark eldar releases complete that codex.
First, a new tyrant model is soon to debut. It has options for the swarm lord. It has some slight differences from the current metal, but is basically similar. I do think it stands between an inch or more higher, but not as tall as a trygon. I did not have an existing tyrant to compare. Wings are supposedly in the kit, but I did not see those.
(this could be a plastic Swarm Lord)
Second, a harpy has been done
For metals,
There is a doom and parasite sculpted. They look as expected. Doom is fairly dynamic, parasite is a bit bigger than I thought and will likely use the larger skimmer base.
And a new yrgarll genestealer in metal...think flash gitz