My understanding based on other stocks that trade on both would be the shares would continue to trade on the TSX and the NASDAQ; the volumes will be separate, as will the prices, since the TSX will trade in loonies and the NAS with bucks. The shares are not differentiated, they are the same shares (one doesn't say "Canadian" and the other "American" and, of course, 99% of us will never see our stock certificate.

I have several that trade on the Toronto and NASDAQ, and some on the Venture and NASDAQ. Often, the move from the old Vancouver (.V) or the TSX to the main Toronto exchange is made first.