I believe the filing of the charge tolled the statute of limitations. I believe the charge will follow the person forever (or until the DA dismisses the charge or the case is resolved), but whether the person would be extradited to Wisconsin is another matter. Still, potentially at least the person could be detained for up to a month every time he or she has contact with law enforcement while Wisconsin makes up its mind about extradition. Having an attorney research the issue in depth and explain the costs and benefits of staying away is likely worth the small investment.
Think of Roman Polanski getting pulled back from Switzerland 20+ years after raping a young girl.
Disclaimer: The above answer is not and should not be construed as legal advice. You should seek legal representation before making any important legal decisions. The exchange above does not create an attorney/client relationship.