Of course there is that risk, but realistically not within the lifetime of the camera.
Olympus are on-board with the M4/3 thing too, and in fact it may be their best bet for survival; to take advantage of the increased flexibility that M4/3 offers to produce some revolutionary new cameras.
So there will be some more lenses in 2009, and more after that. Will the M4/3 system still be around in 2020? Very likely.
Panasonic are not about to go out of business. They are a very large company who want to play in the whole consumer electronics game, like Sony. They are doing very well in the P&S market too. I personally would bet that they have a more secure financial future than Nikon or Leica for example.