The dutch website tweakers.net had a small talk with Matt Spoor from Panasonic Netherland. And he says “possible (G1) successors introduced in March“. Tweakers.net also says (google translation) “This could mean that besides a G1-successor even more new models in the pipeline, with possibly a replacement for the current GH1 Lumix camera.”
P.S.: Thanks to the guy who sent me the link!