Yes, I think Scott Walker's recent recall investigation opens up the possibility of Mitt Romney run for the White House in 2016. I think that Mitt Romney can not accept losing and will try again in 2016. He is a driven man and will not give up his quest to become president.
Having made a much bigger name for himself in the last presidential election, and now with news of Scott Walker's recall investigation, it would be incredibly unlikely for Mitt Romney to not take the opportunity to run in the 2016 presidential election. It remains to be seen if he will be one of the major players, but I would be surprised if he didn't throw his hat into the ring.
I don't think that Scott Walkers recall investigation has much to do at all with Mitt Romney. Mitt stood up to a slew of candidates in 2008, and came out ahead of them. Scott Walker's recall fiasco hurts his run for presidency, but that has little impact on Mitt Romney's decision. If Mitt Romney decides not to run in 2016, Scott Walker would have played no roll in that decision.
Romney is over, people would do well to move on. This is not really for or against Romney or any of his positions, but rather the truth that a presidential candidate who runs today and loses can pretty much definitely never run again - it would not do well in the public eye.
No, Scott Walker's recent recall investigation, although shady, will not likely lead to the possibly of a White House run for Mitt Romney in 2016. They are members of the same party, but really the recall investigation does not seem to be related to the possibility of Mitt Romney running for President another time.