When my wife first got into swinging, she absolutely wanted me involved in MFMs. Insisted on it, even. So, we did. As time went on, that requirement loosened, and I found I really enjoyed watching her have sex, and she enjoyed me watching her. We eventually progressed to solo dates. She would come home and while we made love she would tell me all about the evening. Further on, she had full on boyfriends (in series, not parallel :) ) and had a couple of overnight weekends with one of them.
The point? Things can change (and likely will) over time. If your wife decides to cross this bridge, she may very much want a full on MFM for a while, then maybe want to change things up. Assuming you're all ok with everything, support her as she moves through this. If there's something you don't like though, make sure she's aware of it, and the communication lines are wide open.