In short, no.
If Blu-ray does well, it will help, but probably not significantly. Maybe if all these predictions for super-spiking HDTV penetration come to fruition it could be major. People who are going to be buying the PS3 for the forseeable post-launch future are already inclined to buying HD movie technology to begin with. PS3 can help Blu-ray a hell of a lot more than Blu-ray can help PS3. So, in essense, the reverse is true... if PS3 dominates remotely like PS2, it would be hard to imagine Blu-ray losing to HDTV, though there is DVD to worry about.
If it fails, well, it still plays games. Outside of some poor press, people aren't going to stop buying the thing because it isn't primarily a movie player to begin with.