There has been talk (for quite a while now) of Chris Benoit and Dean Malenko doing a match at the ECW One Night Stand PPV and dedicating it to Eddie Guerrero. Malenko being able to get into ring shape in time for the match or not is probably the only thing that could prevent it at this point, as he likely wouldn't want to go through with a match dedicated to Eddie unless he could give his 100%.
Right now it doesn't look like Benoit would be a full-time part of the new ECW. Occasional appearances in ECW by Benoit are much more likely as things stand right now. However as the past few days have shown, things can change very quickly.