I always thought that if they all seemed to have a beef with Eric Martin (which is a shame as he always comes across as a nice humorous bloke in interviews), they should get another singer and carry on under a different name.
I always thought that Richie Kotzen, Pat Torpey, Marco Mendoza and a new singer (Philip Bardowell or David Victor for example) should get together under the name "Actual Size" and play Mr. Big tunes alongside Richie & Marco's solo stuff and write new material together, as the stuff Marco & Richie wrote for Marco's solo album was very similar to the stuff Richie did for Mr. Big.
However if Billy Sheehan has no beef playing with the guys (except Eric), why don't these 4 go out together and have Richie, Paul & Pat sing lead vocals, and include stuff from their solo careers (to rub the ego's a bit) and build the set around Mr. Big. They technically are Mr. Big, and they technically wont have replaced Eric as such... just not included him.
It will be interesting to see if this leads to anything.
It would sell big in Japan, as they all have success as solo artists and session musicians and as Mr. Big over there.
Niv