I don't think they can hit them with lawsuits. Fines maybe, and repercussions (like not allowing them to sell Nintendo stuff), but only if they can actually verify that the store broke street date. I imagine it's not that easy, either - here in Canada, independent/mom and pop stores do it way more often than, say, ann EB Games would.

The simultaneous release isn't even the problem - why do stores have the games over two weeks early? No wonder some stores broke street date...